In these tests clipping region is set for transformed wxDC/wxGCDC (with changed device origin, logical origin and scale) to check if all these transformations are taken into account in the clipping box calculations.
Flushing native Direct2D renderer (invoking wxGCDC::Flush() -> wxGraphicsContext::Flush() -> ID2D1RenderTarget::Flush()) is apparently not enough to update underlying DC (with selected in bitmap) and therefore we have to destroy the renderer (which in turn invokes ID2D1RenderTarget::EndDraw()) to do so.
1. Added checking if actual drawing output is really clipped at the edge of the clipping box.
2. Added tests for wxGCDC with GDI+, Direct2D, Cairo renderers under wxMSW.
3. Added new test to check calculations for bounding box set entirely outside DC area.
