-Codechange: Deduplicate the image rendering functions.

git-svn-id: https://freerct.googlecode.com/svn/trunk@1246 d3bf82d2-0c16-e458-5408-27be57bd1276
-Fix: 32bpp image rendering.

git-svn-id: https://freerct.googlecode.com/svn/trunk@1247 d3bf82d2-0c16-e458-5408-27be57bd1276