Add texture brush test shapes.
Breaking change, in progress: Texture brushes now paint relative to the origin of the object being painted. In other words, when a rectangle is painted with a texture brush, the origin of the brush will be aligned with the top-left of the rectangle. An offset can be applied via the brushes' Transform. This breaking change is needed because the previous implementation did not have a clean specification and relied on knowing the current graphics transform on iOS and Mac. The current checkin introduces the new behavior for Windows. Subsequent checkins will fix Mac and iOS.
Mac/iOS texture brush fixes, in progress. The translation is note quite correct yet.
Fix for texture brush origin. At this point iOS works! (The test app has revealed an existing bug in the gradient brush handler.) Now to test Mac - hopefully there are no issues there either.