[Experimental transpiler] support for addInitializer

[pabloalmunia]

We have beed added the support for addInitializer() (see #398) into the experimental transpiler:

https://javascriptdecorators.org/

Please, share we us your opinion about the transpiler result.

[pabloalmunia]

We have added the @init: option with field decorators. There are these cases (every link have an example):

	public	private
instance	public field public field with accessor	private field private field with accessor
static	static field static field with accessor	static private field static private field with accessor