Fixes #3125

The service isn't online, and on the long term, mmdb will likekly be
replaced with other services from the modding community.

Enable the server to request the client to reconnect.

This can be done with the now extended minetest.request_shutdown([reason], [reconnect]) setting.

The Irrlicht engine supports antialiasing, and Minetest already supports
saving an antialiasing setting in its configuration file.  However,
Minetest lacked UI elements to set this setting, and previously the only
way to enable the feature was by hand-editing the configuration file.

Add a drop-down menu that can enable antialiasing.

Change the name for texture pack description files from "info.txt" to "description.txt" in order to keep the naming consistent between description files for both mods and texture packs.

Also add backwards compatibility for texture packs that use "info.txt", and note in the log that "info.txt" is depreciated.

- Stop attempting to start a world when no world's created/selected in server tab
- Better world's indexes handling between subgames lists

-> remember the previously loaded serverlist, and use if new one failed
-> show a "loading" serverlist

* abort if theres no active timer
* only reduce the timer.time of all timers when its necessary
* move updating timers_to_add into a seperate function

Now logs

ACTION[ServerThread]: player sets time to 6:03

instead of

ACTION[ServerThread]: player sets time to 6:3

  * The time command now accepts parameters in the form <hour>:<minute>,
    and if invoked with no parameters returns the current time in said format.

Items dropped into unloaded map space will crash game so here's a fix...

Don't ident too much, and add a comment.

On calling clear_redistered_biomes the registered_biomes table is cleared
by creating a new empty table, but the pointer is not updated to point to
the new one. So after calling more register_biome, the registered_biome
table always contains 0 items, which is an error. Instead, the table is
cleared by removing all its items so the pointer (minetest.registered_*)
remains valid.