Fixes #2497.

Fixes #2037

Client now informs about incompatible servers from the list, this permits to prevent the protocol movements.
Server announces its supported protocol versions to master server

Fix unused (and so, broken) enable_rollback_recording. This option must be reloaded at server loop but loaded when server starts, for data consistency (not a hot load variable)
ok @ShadowNinja

Fixes #2293.

https://forum.minetest.net/viewtopic.php?f=6&t=11201
Fixed this bug.

This reverts commit 7b17b905.

Add optional core.pos_to_string decimal place rounding
Move core.string_to_pos to builtin/common/misc_helpers.lua for consistency

Also add a Lua API and chatcommand for this

Set builtin formspecs to autoscale in order to get consistent formspec look and feel
Uncouple label positioning from font size (May break some formspecs but is required to allow manual font adjustment)

Also rewrite mapgen registration for static initialization

Add minetest.get_mapgen_params()
Deprecate minetest.register_on_mapgen_init()

Fixes #1807: When the server list finishes downloading, the local server
list resets in certain conditions