A handful of minor fixes to various things
Print playername when failing to read playerfile and ignore files starting with .
Decoration: Add support for zero probability, fix breakage from last commit
Add support for IPv6
Two new configuration options are added:
     - "enable_ipv6" to enable/disable the overall use of IPv6
     - "ipv6_server" to enable/disable the use of IPv6 sockets when running
       a server (when "enable_ipv6" is enabled)
New math mapgen with fractal based worlds
Math mapgen fix, ip show on connect, pathfinder segfault fix
Cavegen: fix division by 0 with abnormal max tunnel diameter sizes
Add LuaVoxelManip