Merge pull request #40 from FLHerne/master

Minor tweaking
Minor map tweaks - really needs some more map-specific settings to make sense though
Merge branch 'master' of github.com:BinkyToo/CCDQuest
new portal icons that make sense - not pretty though
slightly prettier portals
minor tile tweaking
Sanify terrain images, remove 'random' from tile.

Tile array now stores Surface references rather than list indexes.
All sprites are now selected at load time, makes things much tidier.
Stop damage/fire using 'random'. Remove 'damage'.