Consider OpenFL .hxp files as haxe files

see http://www.openfl.org/documentation/projects/project-files/hxp-format/
FileHelper.IsHaxeFile() -> IsHaxeExtension()
Merge branch 'development' into openfl_hxp

Conflicts:
	External/Plugins/ASCompletion/Model/FileModel.cs
Add snippets for do..while loops
Error handling for missing Loom SDK / loom.bat
Fixed AIR SetupApplication templates
Merge pull request #438 from Gama11/doWhileSnippets

Add snippets for do..while loops
Merge pull request #440 from Gama11/LoomSDKError

Error handling for missing Loom SDK / loom.bat
Merge pull request #439 from Neverbirth/airimprovements

Fixed AIR SetupApplication templates
Merge pull request #421 from Gama11/openfl_hxp

Consider OpenFL .hxp files as haxe files
Fixes Null References Error from 'new FileModel(null)'
Keep the original method signatures and add overloaded methods.
Merge pull request #441 from SlavaRa/improvement-ASCompletion.Completion.ASComplete

closes: issue #382