Moved primitive drawing calls in to Surface

[sir_nacnud]

I moved the primitive drawing calls in to the Surface class as discussed here: https://openxcom.ninex.info/forum/index.php?topic=124.0

I have added the following functions to Surface:
drawRect()
drawLine()
drawCircle()
drawPolygon()
drawTexturedPolygon()
drawString()

These functions should be used instead of directly calling SDL_gfx functions.  Let me know if there is anything I have missed.  See attached patch.

[SupSuper]

Good job, added to SVN.