This commit adds chat2 support (https://github.com/minetest-mods/chat2).
Tested with MT/MTG 5.0.1 and works pretty well.
If there's any bug/error/typo, please tell me, so, I can fix it.
With this function enabled, players with "tp_admin" privilege teleport immediately to the specified player.
Otherwise, it will send a request to the specified player.
I've changed the license to complete another task from the TODO list (and to make it compatible with MT/MTG and many other games/mods) .
Please decide if it was correct to change the license.
If you do not like this change, please tell me, so, I can revert these changes.