Add LiveScript syntax

The file `LiveScript.sublime-syntax` is a pure export from a licenced version
of Sublime Text, Version 3.1.1, Build 3176 with
assets/syntaxes/02_Extra/LiveScript/Syntaxes/LiveScript.tmLanguage as the source
file.

tests/syntax-tests/source/LiveScript/LICENSE.md

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+The `livescript-demo.ls` file has been added from https://github.com/paulmillr/LiveScript.tmbundle under the following license:
+
+The MIT License (MIT)
+
+Copyright (c) 2012 Paul Miller (http://paulmillr.com/), Jeremy Ashkenas
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

tests/syntax-tests/source/LiveScript/livescript-demo.ls

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+a = -> 1
+const b = --> 2
+var c = ~> 3
+d = ~~>
+e = (a) -> (b) ~> (c) --> (d, e) ~~> 5
+dashes-identifiers = ->
+  a - a
+  b -- c
+  1-1 1- -1
+  a- a
+  a -a
+
+//abc #eaze #@ //
+//
+a #baze
+//
+
+publi
+if it is \abc and ($-y = !(a,) ->) ~= map //a#//
+then match that | _ | otherwise => implements $("#abc #@a")
+
+switch |a=>b
+| a then b
+
+if a => b else c
+
+underscores_i$d = ->
+/regexp1/ and //regexp2//g
+'strings' and "strings" and \strings
+([2 til 10] or [1 to 50])
+  |> map (* 2)
+  |> filter (> 5)
+  |> fold (+)
+
+setTimeout _, 3000 <| do-stuff
+_.map; _abc; __
+
+
+class Class extends Anc-est-or
+  (args) ->
+
+copy = (from, to, callback) -->
+  error, data <- read file
+  return callback error if error?
+  error <~ write file, data
+  return callback error if error?
+  callback()
+
+$(\#gafBr).text $t.fmtFloat(efb.gaf)
+
+->
+~>
+~~>
+-->
+# Comment
+/* Comment */
+# error, data <- read file
+  /* error, data <- read file */
+
+add = (a=1, b=2) --> a + b
+add 1 2
+do-stuff!
+do-stuff? #
+do-stuff? 1
+do-stuff + 1
+@do-stuff +1
+@do-stuff /1
+a b c |> d <| e f(g)
+'cats' is 'cats'
+'cats' `_.is-insensitive` 'CATS'
+setTimeout _, 1000 <| !-> console.log 'Who summoned me'
+private-list = yield @get-private-list!
+switch | true => "#@@spaghetti"
+~function add a=1, b=2 => a + b
+row.0._id
+new Spaghetti
+(++a++) (++ 2 ++)
+(.cool.) (+  a  -) (/ 2 *)
+(ina -a in) (-> a)
+(ina in$a)
+(a is-in)
+(in)
+((((((+ a((a))))))))