Use configdir.c instead of hardcoded paths for the list of DHT servers.
Modified cmakefile to move the serverlist to the proper directory.
Tested on GNU/Linux.
Made configdir check XDG_CONFIG_HOME for config dir
Merge pull request #494 from frh/master

Made configdir check XDG_CONFIG_HOME for config dir
Merge pull request #491 from loadletter/master

Store data and DHTservers in .config/tox
Prevented possible MITM attack.

Friends must now send to themselves at least one encrypted ping packet
every 5 seconds.

If no encrypted ping packets are recieved from a friend within 10
seconds the connection is killed.
Realloc apparently doesn't always behave like free() if size is zero.
Fixed segfault.
Merge with upstream