fixed blend factors for filter passes (closes #188)

The problem became visible with many passes of a blur filter, leading to wrong alpha values.
Merge branch 'master' of github.com:PrimaryFeather/Starling-Framework
now disposing children in reverse order (closes #190)
now gracefully shutting down on unhandled context loss (closes #191)
using actual size of vector in dispose, to avoid problems with subclasses (refs #190)
removing REMOVE_FROM_JUGGLER event listener in 'Juggler.removeTweens' method (refs #192)
fixed re-adding tween to juggler in 'onComplete' method (closes #193)
added 'onRepeat' and 'onRepeatArgs' callback to tweens
added 'repeatDelay' property to tweens (closes #194)
fixed missing args caching (refs #193)
now disposing context at the very end (closes #195)

to be sure that it's disposed *after* all other CONTEXT3D_CREATE event listeners have been removed.
now ending all touches in case of an interruption (Event.DEACTIVATE)
added missing import
now avoiding error "invalid context3d bounds" in constrained mode

Constrained mode requires the back buffer to be within the stage bounds. This change circumvents this by clipping the viewport against the stage bounds and using this clipped version internally.
now saving a reference to root object directly (closes #196)
fixed bug when creating a SubTexture / calling Texture.fromTexture() from a RenderTexture

Before this fix, the displayed region was wrong.
ignoring xOffset on first char of each line (closes #189)
added pressure and size information to touch
fixed null reference when using shared context (closes #199)
added reset method to DelayedCall class (refs #202)