Posted version 0.99g, fixes a possible crash

Version 0.99g is a minor bugfix release that fixes two bugs:

• A potential crash (via unhandled exception) when accessing a computer. This was caused when you had a selected message in a computer at an earlier level that was at a greater index than the number of items in the computer in a later level (e.g. if in level 2 you read the fourth disk note before changing the map and then tried to use the computer in level 3, the game would crash)
• Windows only: exiting the game could leave the gdipetra.exe process running, this was fixed

I was planning this version to be the one that introduces a hardware accelerated version, but i was busy with other things and i wanted to fix these two bugs (especially the first one that can cause someone to restart the game). I didn't update the editor for this version since it wasn't really affected by any of those.