Made the resource manager retrieve the OD installation path at load time.

I also made it so the ./resources.cfg file is tested first to override the data path to "./",
to still permit developer builds.

Needs testing though to make sure.

Should help with #58
Made the level loading work even on system-wide installation.

Music and sounds are already working, but scripts aren't yet.
I made the server send a filename relative to the installation path to the client(s).

Due to the sharable nature of levels, we might later want to just send a filename + SHA/MD5
and let the client search through the bundled levels + user custom ones.
Fixed AS script path in initialization.

Also fixed the console.as script by dropping an obsolete console command. (aithreads)
Oops, forgot to make the creatures.def file follow the installation path.
Dropped load/save maps from TGA files.

This is obsolete, half-finished and non-working code that shouldn't have been pushed
in the common repository in the first place. Sorry Tom.

I also removed some obsolete console commands.
Merged the getMapName and getMapDescription in a more efficient function.
Improved the display of player slot and AI in the map descriptions UI.
Merge pull request #184 from Bertram25/od-data-path

Made the resource manager retrieve the OD installation path at load time...