Rental sizes - and server crashes

SirKewberth

So... An enterprising qbee decided to test the limits of the rental system by renting out an entire 100x100 room. Unfortunately this didn't work very well on our end, and caused problems. So we added a 50x50 limit to rental plots. Hopefully this won't affect too many if anyone. We're restarting the server now to address it (and maybe later if it needs more tweaking).