Fix anticheat
Allow mods to listen to cheat detections using minetest.register_on_cheat()
Fix server getting completely choked up on even a little of DoS

* If client count is unbearable, immediately delete denied clients
* Re-prioritize the checking order of things about incoming clients
* Remove a huge CPU-wasting exception in ReliablePacketBuffer
Change large amount of objects to be configurable via a setting in minetest.conf (max_objects_per_block).
Add texture pack selection to main menu
Dont show gamefilter in TP tab
Make freetype usage configureable by a setting