total refactoring of the texture restoration process on a context loss

You can now restore a texture using a "onRestore" callback function. The default behaviour is still to keep the original bitmap data around for the restoration, but you're able to override this by creating your own restoration mechanism -- which might reload the file from disk, recreate it from an Embedded Bitmap, etc.
using 'onRestore' functionality from AssetManager; small 'uploadData' adjustments

The AssetManager now loads the textures from the original sources in case of a context loss. It can thus restore all textures without having to cache any bitmap data.
using 'onRestore' functionality in TextField (on TTF rendering)

Thus, text fields no longer need to cache their bitmap data for a context loss.
added 'Texture.fromEmbeddedAsset' method and using it in samples
added GC hints after AssetManager loading
fixed recursion error when applying filter on flattened object (closes #316)
Switched to FM6
Fixed snapshot version
Use a property for playerglobal version
Merge pull request #352 from morvans/master

Maven pom.xml update
added support for generic XML and JSON data to AssetManager (closes #241)
DisplayObjectContainer: return from setChildIndex() immediately if the index is the same to avoid calling splice() for no reason
Merge pull request #353 from joshtynjala/setchildindex

DisplayObjectContainer: return from setChildIndex() if index is the same
now recognizing utf-16 XML and JSON files
Merge branch 'master' of github.com:PrimaryFeather/Starling-Framework
removed 'isNaN' call to avoid memory allocations (closes #355)
now using RectangleTexture for 'Texture.empty()', as well (closes #354)

Attention: arguments of 'Texture.empty()' have changed!
updated path to my local AIR sdk
minor documentation addition
fixed background loading in demo and scaffold