Use "auto& resource=GetResource()"

Avoid an unnecessary AddRef/Release call
Add effects that use float[] property type, aka "blob" in D2D - ConvolveMatrixEffect, DiscreteTransferEffect, and TableTransferEffect
Formatting tidyup: remove unwanted double space
Change uint effect parameters to regular int (more idiomatic C#/WinRT API style)
CanvasControlTestAdapter::FireCompositionRenderEvent() now always passes nullptr for the sender

IRL, the sender will always be null (since it's on a static).  The current behavior of the tests of passing in CanvasControl is certainly not something we'd ever expect to see.
Clean up ICanvasControlAdapter interface

- remove IsDesignModeEnabled in the name of tell-don't-ask
- nothing needs the token returned by AddDpiChangedCallback, so remove it
Remove dangerous cast from ICanvasImageSource to CanvasImageSource

CreateDrawingSessionWithDpi and CreateDrawingSessionWithUpdateRectangleAndDpi are not IFACEMETHODs
Check result of Callback()
CanvasControl now handles CompositionTarget.SurfaceContentsLost - fixes #23
Enable CanvasBitmap CPU write.
Better error messages when effect properties are set to incorrect types
Add the burning text example.
CanvasControl now tracks window visibility to ensure it doesn't attempt to render when the window is not visible
Improved async support

Added a continuation mechanism, so one async operation can be registered to run after
another has completed. This simplifies the bitmap from-URI functionality, which needs to
trigger our async decode operation only after the URI has been successfully opened.

Merged the AsyncOperation and AsyncAction implementations, reducing duplicated code.

Use proper runtime class names for these generic interface implementations.
Use RegisteredEvent to manage event registration
CanvasControl now tested via events rather than directly calling the event handlers

Previously, all the tests passed even if CanvasControl didn't register the Loaded or SizeChanged events.

Now the tests fail if the control doesn't respond to these events.

In addition some of the resizing tests were explicitly requesting redraws; now these tests use the control's built-in redraw-on-resize behavior (and will fail if this behavior breaks).

Also replaced a magic '1000' with a variable.
Merge branch 'master' of https://github.com/Microsoft/Win2D
Make m_canvasImageSource a ComPtr<CanvasImageSource>
CanvasControl calls Trim() on its device when the app suspends
Factor out common code in Add*Callback helpers