Increase the map limit for skirmish mode

[Riccardoman]

I know it's an issue from the original source code, but could you make it possible to increase this limit? I have currently 280 custom maps

[zturtleman]

It's raised compared to original source code. I may consider switching to unlimited number of maps in menu in a future update but no guarantees.

The limit is a mix of max string length for all scripts/*.arena filenames and max maps. The max maps could be switched to dynamically allocated but I would also need to extend the engine CGame API for file listing to be able to get all script/*.arena filenames.