Special-case wxStaticBitmap::Scale_Fill with SVG file

[KeyWorksRW]

Description:

When a wxStaticBitmap has wxStaticBitmap::Scale_Fill set and an SVG file is specified for the bitmap's bundle, it would make sense to set the SVG file to the size of the bitmap. Otherwise, the svg's default size will be converted to a bitmap and then scaled up/down which typically looks terrible. Since SVG files are designed to scale, it makes more sense for the SVG file to rescale itself rather than the bitmap.