WIP: Increase max network packet sizes

[VReaperV]

Increase the maximum length of a network message from 32768 bytes to 262144. Also increased max packet length from 1400 bytes to 265000 bytes, because packet fragmenting is not working correctly with larger message sizes.

This allows for more entities on the map, and brings the soft limit on the amount of buildings from ~250 to ~2k.

Tested with https://users.unvanquished.net/~sweet/layouts/spacetracks/humanpve1.dat (layout for map spacetracks): doesn't crash anymore, the game loads fine.

I'm getting a stack overflow when trying to connect to a server for some reason though.