Call OnUnload when closing a window
Mac: Don’t trigger Closing/Closed events when hiding the main form
Add Drawable.SupportsCreateGraphics instead of requiring using try/catch to detect support
Windows: Always use synchronization context to Invoke/AsyncInvoke, e.g. when main form is closed, causes issues
Wpf: Set priority to background when invoking to avoid throttling the message loop
Direct2D: updates to add Texture/Linear brushes, and handle creating pens/brushes before the RenderTarget is available
Direct2D: updates to GraphicsPath to implement ellipse, rectangle, arc, and AddPath (AddPath still needs proper combining functionality)
Remove IGraphics2 interface and Begin/EndDrawing, in lieu of using the D2D Drawable which does the begin/end for us
Eto.Test.Wpf: DrawLoop tests now doesn’t use tiling to provide a better visual update
Eto.Test: DirectDrawingSection is now DrawLoopSection
Eto.Test: Remove DrawingToolkit from Eto.Test, and pass the Generator to the test instead and ensure everything uses the correct generator when created (less complexity in the tests, the better)
Eto.Test: Test images can now be passed a generator for the d2d tests
Merge remote-tracking branch 'picoe/develop' into dev3

Conflicts:
	Source/Eto.Test/Eto.Test/DynamicLayoutExtensions.cs
Remove obsolete file.