Add ESP8266 core v2.6.2 (#905)

* Add ESP8266 core v2.6.2

* Upstream ESP8266 Wifi fixes

* Replace disable_interrupt with InterruptLock C++ class

* Update code to use InterruptLock

* Lint

* Update dht.cpp

* Improve InterruptLock docs, mark as ICACHE_RAM_ATTR

* Fixes

esphome/core/helpers.h

@@ -133,16 +133,38 @@ uint16_t encode_uint16(uint8_t msb, uint8_t lsb);
 /// Decode a 16-bit unsigned integer into an array of two values: most significant byte, least significant byte.
 std::array<uint8_t, 2> decode_uint16(uint16_t value);
 
-/** Cross-platform method to disable interrupts.
+/***
+ * An interrupt helper class.
  *
- * Useful when you need to do some timing-dependent communication.
+ * This behaves like std::lock_guard. As long as the value is visible in the current stack, all interrupts
+ * (including flash reads) will be disabled.
  *
- * @see Do not forget to call `enable_interrupts()` again or otherwise things will go very wrong.
+ * Please note all functions called when the interrupt lock must be marked ICACHE_RAM_ATTR (loading code into
+ * instruction cache is done via interrupts; disabling interrupts prevents data not already in cache from being
+ * pulled from flash).
+ *
+ * Example:
+ *
+ * ```cpp
+ * // interrupts are enabled
+ * {
+ *   InterruptLock lock;
+ *   // do something
+ *   // interrupts are disabled
+ * }
+ * // interrupts are enabled
+ * ```
  */
-void disable_interrupts();
+class InterruptLock {
+ public:
+  InterruptLock();
+  ~InterruptLock();
 
-/// Cross-platform method to enable interrupts after they have been disabled.
-void enable_interrupts();
+ protected:
+#ifdef ARDUINO_ARCH_ESP8266
+  uint32_t xt_state_;
+#endif
+};
 
 /// Calculate a crc8 of data with the provided data length.
 uint8_t crc8(uint8_t *data, uint8_t len);