-Scene edit state is saved outside the scene now, to avoid changes .tscn files when nothing really changed
-Created a VariantWriter helper to unify all variant to text writing
-Moved SceneFormatText writing to VariantWriter
-Moved ConfigFile to use VariantWriter and VariantParser, added compatibility mode for old .cfg files that use engine.cfg format
-Fixed many bugs in stretch mode
-Fixes to camera project and unproject as consequence of the above
-added setget to script (documented in script doc)
-more fixes to collada exporter for blender
