Fixed bug with TCP.

Don't increment nonce if packet was discarded instead of being sent.
Fixed TCP bug.

Packet was being copied with a wrong, smaller length.
added priority packet system for TCP server
fixed some issues
Merge branch 'notsecure-split-video'
applied priority queue changes to the TCP client too
fix memory leak
Merge branch 'JFreegman-memleak'
Merge branch 'split-video' of https://github.com/notsecure/toxcore
Fixed possible bug with TCP nonce not getting incremented.
Build system now automatically enables epoll support in TCP server
when supported.
Spread packets over many TCP relays instead of just using the first one.
Set some functions as static, fixed warning.
Removed useless function.
declare calculate_sum_sq static inline
remove this too
Merge branch 'lllllllleeeeeeeeellllll' of https://github.com/stal888/ProjectTox-Core
Improved protocol and cleaned code a bit
Added addr_parse_ip() to network.h header.

Removed useless semicolons.
LAN discovery should now work on windows machines with multiple
ethernet devices.

Added some code to get real adapter broadcast addresses on windows.