raised AIR xml namespace references to 4.0
updated asdoc path to latest revision

Sorry for that being rather specific to my own system :-/
fixed asdoc comment
added support for automatic profile selection (closes #337)

Requires AIR 4.0 to work. Per default, Starling now picks the best available profile. Alternatively, you can pass a vector or array with the profiles you want to support.
simplified mathematics of 'DisplayObject.transformationMatrix' setter
fixed missing textField-dispose in Button; fixed text alignment getters (refs #456)
added missing null reference check
numChildren getter changed to be inlined.
Merge remote-tracking branch 'refs/remotes/upstream/master'

Conflicts:
	starling/src/starling/display/DisplayObject.as
now disposing objects when they are overwritten by new ones in AssetManager (closes #467)

Furthermore, added dispose/clear calls for XMLs and ByteArrays in 'dispose' method.
added missing support for Vectors in "profile" argument; now picking lowest available profile in older AIR versions (instead of the first list element) (refs #337)
Merge remote-tracking branch 'refs/remotes/upstream/master'
added more api docs about render context and context loss (refs #337)
now surviving a context loss happening while processing the asset queue (closes #472)
added missing 'handleLostContext' check
now enforcing passing of single profile to Starling constructor in shared context scenarios
added 'transformationMatrix' property to 'SubTexture' class (closes #470)
Merge remote-tracking branch 'refs/remotes/upstream/master'
changed automatic profile selection to prefer known profiles in fallback solution (refs #337)
fixed position of clear call in main render method (closes #468)