add mapgen

Added the possiblity of generating maps to spring.

When a MapSeed is added to script.txt, the generator creates an archive in memory using the name given in MapName.

I've added a CVirtualArchive class which is an archive that can be created and manipulated during runtime (unlike the existing ones which require files to be on disk)

CMapGenerator contains all the base code for map generation, such as creating the actual archive and putting the smf, smt, and mapinfo.lua in.

CSImpleMapGenerator is a simple example generation class (to be improved upon) which generates a flat landscape and places spawnpoints.

In the future, a lua-based map generator could be added for example, so map scripts could be used instead of actual maps, which are much smaller and would add a ton of variety.