Added compilation flags for choosing between gdiplus and direct2d implementations of wxGraphicsContext
Added compile guards around msw/graphics.cpp and msw/graphicsd2d.cpp
Added msw/directd2d.cpp to {make,project} files
Fixed wxD2DRenderer::GetVersion method having wrong signature
Removed duplicate default argument values from method definitions
Fixed wrong class name for wxD2DRenderer in declarations
Removed duplicate method implementation
Removed duplicate default argument values from method definitions
Removed method not inherited from wxGraphicsContext
Added explicit calls to wxGraphicsContext super constructor
Added dummy return values to unimplemented methods
Added static methods to wxGraphicsRenderer to allow the creation of both direct2d and gdi+ renderers, when available. Also updated wxGraphicsRenderer::GetDefaultRenderer() to return the best available renderer.