Fix HAXE-367

-plugin now compiles with intellij 13.1.1
-fixes http://youtrack.jetbrains.com/issue/HAXE-367

I know nothing about writing intellij plugins and very little about haxe.  These changes are made based on guesses and assumptions made from the previous and current API.  I also incorporated changes made in PR 8 (https://github.com/JetBrains/intellij-haxe/pull/8).  That being said so far it's huge improvement on plugin functionality.

Please review carefully!