-Codechange: Hugely simplify the recolouring storage.

- Delete the RandomRecolouringMapping class.
- Use Recolouring both for unassigned and assigned colours, copying from type to instance.
- Don't pre-compute all 8bpp recolour tables, store the recolour mapping, and compute on the fly.


git-svn-id: https://freerct.googlecode.com/svn/trunk@1155 d3bf82d2-0c16-e458-5408-27be57bd1276