[NO SQUASH] Maintenance work

[SmallJoker]

See commit descriptions for reference.

The deprecation warnings can be seen with the setting deprecated_lua_api_handling = log.

[SmallJoker]

Will merge in a few days unless there are objections.

[rautyrauty]

I also suggest moving changelog to a separate file and updating the version to 1.8.0.

[SmallJoker]

@rautyrauty Good idea. The changelog is often not very interesting. I'm however not wiling to track versions of this repository. It's easier to move it to rolling release, like now done in Minetest Game and other minetest-mods repositories that are kept alive by new contributors.

[rautyrauty]

It would be good to send the sources to the src folder, with the exception of init.lua and similar files needed for mod initialization.