Fixed bug where a window created fullscreen and hidden would get activated and "shown" but never actually be visible.
This is the case with the Steam In-Home Streaming client.
Exposed the font character size and SDLTest_DrawCharacter() to make it easier to do custom debug text layout
Recreate render target textures when the D3D device is being reset, and notify the application using the SDL_RENDER_TARGETS_RESET event when this happens.