videosoftware: Added hack to bypass xfb just so fifoplayer works.

Fifoplayer depends on the old behaviour of videosoftware (and the other
hardware backends in non virtual/real xfb modes) where the framebuffer
gets rendered directly to the screen.

Really fifoplayer should call BeginFrame/EndFrame when it finished
rendering a frame, but adding this hack back in is simpler.
videosoftware: Provide a more elaborate comment on the FifoPlayer support hack.
videosoftware: More coding style fixes.
Merge pull request #118 from neobrain/videosoftware-bypass-xfb-hack

Software renderer: Restore FifoPlayer support by emulating hardware backend behavior.