🏗 Merge C++ into python codebase (#504)

## Description:

Move esphome-core codebase into esphome (and a bunch of other refactors). See https://github.com/esphome/feature-requests/issues/97

Yes this is a shit ton of work and no there's no way to automate it :( But it will be worth it 👍

Progress:
- Core support (file copy etc): 80%
- Base Abstractions (light, switch): ~50%
- Integrations: ~10%
- Working? Yes, (but only with ported components).

Other refactors:
- Moves all codegen related stuff into a single class: `esphome.codegen` (imported as `cg`)
- Rework coroutine syntax
- Move from `component/platform.py` to `domain/component.py` structure as with HA
- Move all defaults out of C++ and into config validation.
- Remove `make_...` helpers from Application class. Reason: Merge conflicts with every single new integration.
- Pointer Variables are stored globally instead of locally in setup(). Reason: stack size limit.

Future work:
- Rework const.py - Move all `CONF_...` into a conf class (usage `conf.UPDATE_INTERVAL` vs `CONF_UPDATE_INTERVAL`). Reason: Less convoluted import block
- Enable loading from `custom_components` folder.

**Related issue (if applicable):** https://github.com/esphome/feature-requests/issues/97

**Pull request in [esphome-docs](https://github.com/esphome/esphome-docs) with documentation (if applicable):** esphome/esphome-docs#<esphome-docs PR number goes here>

## Checklist:
  - [ ] The code change is tested and works locally.
  - [ ] Tests have been added to verify that the new code works (under `tests/` folder).

If user exposed functionality or configuration variables are added/changed:
  - [ ] Documentation added/updated in [esphomedocs](https://github.com/OttoWinter/esphomedocs).

esphome/components/mqtt_subscribe/__init__.py

@@ -0,0 +1,3 @@
+import esphome.codegen as cg
+
+mqtt_subscribe_ns = cg.esphome_ns.namespace('mqtt_subscribe')

esphome/components/mqtt_subscribe/sensor/__init__.py

@@ -0,0 +1,27 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import mqtt, sensor
+from esphome.const import CONF_ID, CONF_NAME, CONF_QOS, CONF_TOPIC
+from .. import mqtt_subscribe_ns
+
+DEPENDENCIES = ['mqtt']
+
+CONF_MQTT_PARENT_ID = 'mqtt_parent_id'
+MQTTSubscribeSensor = mqtt_subscribe_ns.class_('MQTTSubscribeSensor', sensor.Sensor, cg.Component)
+
+CONFIG_SCHEMA = cv.nameable(sensor.SENSOR_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_variable_id(MQTTSubscribeSensor),
+    cv.GenerateID(CONF_MQTT_PARENT_ID): cv.use_variable_id(mqtt.MQTTClientComponent),
+    cv.Required(CONF_TOPIC): cv.subscribe_topic,
+    cv.Optional(CONF_QOS, default=0): cv.mqtt_qos,
+}).extend(cv.COMPONENT_SCHEMA))
+
+
+def to_code(config):
+    parent = yield cg.get_variable(config[CONF_MQTT_PARENT_ID])
+    var = cg.new_Pvariable(config[CONF_ID], config[CONF_NAME], parent, config[CONF_TOPIC])
+    yield cg.register_component(var, config)
+
+    cg.add(var.set_qos(config[CONF_QOS]))
+
+    yield sensor.register_sensor(var, config)

esphome/components/mqtt_subscribe/sensor/mqtt_subscribe_sensor.cpp

@@ -0,0 +1,32 @@
+#include "mqtt_subscribe_sensor.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace mqtt_subscribe {
+
+static const char *TAG = "mqtt_subscribe.sensor";
+
+void MQTTSubscribeSensor::setup() {
+  mqtt::global_mqtt_client->subscribe(this->topic_,
+                                      [this](const std::string &topic, std::string payload) {
+                                        auto val = parse_float(payload);
+                                        if (!val.has_value()) {
+                                          ESP_LOGW(TAG, "Can't convert '%s' to number!", payload.c_str());
+                                          this->publish_state(NAN);
+                                          return;
+                                        }
+
+                                        this->publish_state(*val);
+                                      },
+                                      this->qos_);
+}
+
+float MQTTSubscribeSensor::get_setup_priority() const { return setup_priority::AFTER_CONNECTION; }
+void MQTTSubscribeSensor::set_qos(uint8_t qos) { this->qos_ = qos; }
+void MQTTSubscribeSensor::dump_config() {
+  LOG_SENSOR("", "MQTT Subscribe", this);
+  ESP_LOGCONFIG(TAG, "  Topic: %s", this->topic_.c_str());
+}
+
+}  // namespace mqtt_subscribe
+}  // namespace esphome

esphome/components/mqtt_subscribe/sensor/mqtt_subscribe_sensor.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/mqtt/mqtt_client.h"
+
+namespace esphome {
+namespace mqtt_subscribe {
+
+class MQTTSubscribeSensor : public sensor::Sensor, public Component {
+ public:
+  MQTTSubscribeSensor(const std::string &name, mqtt::MQTTClientComponent *parent, const std::string &topic)
+      : Sensor(name), parent_(parent), topic_(topic) {}
+
+  void setup() override;
+  void dump_config() override;
+  float get_setup_priority() const override;
+
+  void set_qos(uint8_t qos);
+
+ protected:
+  mqtt::MQTTClientComponent *parent_;
+  std::string topic_;
+  uint8_t qos_{0};
+};
+
+}  // namespace mqtt_subscribe
+}  // namespace esphome

esphome/components/mqtt_subscribe/text_sensor/__init__.py

@@ -0,0 +1,28 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import text_sensor, mqtt
+from esphome.const import CONF_ID, CONF_NAME, CONF_QOS, CONF_TOPIC
+from .. import mqtt_subscribe_ns
+
+DEPENDENCIES = ['mqtt']
+
+CONF_MQTT_PARENT_ID = 'mqtt_parent_id'
+MQTTSubscribeTextSensor = mqtt_subscribe_ns.class_('MQTTSubscribeTextSensor',
+                                                   text_sensor.TextSensor, cg.Component)
+
+CONFIG_SCHEMA = cv.nameable(text_sensor.TEXT_SENSOR_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_variable_id(MQTTSubscribeTextSensor),
+    cv.GenerateID(CONF_MQTT_PARENT_ID): cv.use_variable_id(mqtt.MQTTClientComponent),
+    cv.Required(CONF_TOPIC): cv.subscribe_topic,
+    cv.Optional(CONF_QOS, default=0): cv.mqtt_qos,
+}).extend(cv.COMPONENT_SCHEMA))
+
+
+def to_code(config):
+    parent = yield cg.get_variable(config[CONF_MQTT_PARENT_ID])
+    var = cg.new_Pvariable(config[CONF_ID], config[CONF_NAME], parent, config[CONF_TOPIC])
+    yield cg.register_component(var, config)
+
+    cg.add(var.set_qos(config[CONF_QOS]))
+
+    yield text_sensor.register_text_sensor(var, config)

esphome/components/mqtt_subscribe/text_sensor/mqtt_subscribe_text_sensor.cpp

@@ -0,0 +1,22 @@
+#include "mqtt_subscribe_text_sensor.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace mqtt_subscribe {
+
+static const char *TAG = "mqtt_subscribe.text_sensor";
+
+void MQTTSubscribeTextSensor::setup() {
+  this->parent_->subscribe(this->topic_,
+                           [this](const std::string &topic, std::string payload) { this->publish_state(payload); },
+                           this->qos_);
+}
+float MQTTSubscribeTextSensor::get_setup_priority() const { return setup_priority::AFTER_CONNECTION; }
+void MQTTSubscribeTextSensor::set_qos(uint8_t qos) { this->qos_ = qos; }
+void MQTTSubscribeTextSensor::dump_config() {
+  LOG_TEXT_SENSOR("", "MQTT Subscribe Text Sensor", this);
+  ESP_LOGCONFIG(TAG, "  Topic: %s", this->topic_.c_str());
+}
+
+}  // namespace mqtt_subscribe
+}  // namespace esphome

esphome/components/mqtt_subscribe/text_sensor/mqtt_subscribe_text_sensor.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/text_sensor/text_sensor.h"
+#include "esphome/components/mqtt/mqtt_client.h"
+
+namespace esphome {
+namespace mqtt_subscribe {
+
+class MQTTSubscribeTextSensor : public text_sensor::TextSensor, public Component {
+ public:
+  MQTTSubscribeTextSensor(const std::string &name, mqtt::MQTTClientComponent *parent, const std::string &topic)
+      : TextSensor(name), parent_(parent), topic_(topic) {}
+
+  void setup() override;
+  void dump_config() override;
+  float get_setup_priority() const override;
+  void set_qos(uint8_t qos);
+
+ protected:
+  mqtt::MQTTClientComponent *parent_;
+  std::string topic_;
+  uint8_t qos_{};
+};
+
+}  // namespace mqtt_subscribe
+}  // namespace esphome