Fixed TilingSprite not render children on canvas

TilingSprite does not render children on 2d canvas. The call to
children's renderCanvas method is missing.
collecting interactive sprites should not happen in reverse
Merge pull request #644 from mattdesl/bugfix-641

Bug fix: Siblings' event priority
update karma version
update karma *again* to latest v0.12
Fix Text.destroy() and fix memory leak in BaseTexture.destroy() if basetexture was from canvas
Added optional FilterArea to displayObject (for optimisation)

Reverted interaction manager (for now) as not working as expected (no
bubbling)
Added removeChildAt method

the ability to remove a child in a specific index.
updated removeChildAt, removeChild, removeChildren
updated removeChildAt and removeChild. removeChildren has now a begin and end value.
removed spaces
Merge pull request #656 from andrevenancio/dev

added removeChildAt, added removeChildren
Fix logic error in DOC
Manually merge #657
Implemented animationSpeed for Spine animations.
Default value is 1.
This is simply the "timeScale" value from the Spine runtime, but with a more friendly name.
Fixed anchor point bug in canvas

tilingSprites anchor was not being respected in the canvas renderer
Add scaleMode params to FilterTexture and RenderTexture
Minor Bug fixes and Added DropShadow to text

Added drop shadow to text
Fixed bug with tiling texture rendering in canvas when not yet loaded
Switched Cross origin to be true by default
Added support for dropShadowColor.

Initial support for colouring of drop shadows on PIXI.Text();
Merge pull request #668 from TomSlezakowski/dev

Added support for dropShadowColor.