Fix android build using hardcoded path for data instead of using the one fetched by android api on init.
Fix android missing version information

Broken by 6bc4cad0, e.g.
  minetest --worldname world
would be parsed as
  minetest --worldname --worldname

Broken by 6bc4cad0 because database-redis.h
depended on settings.h to include filesys.h.

Caused by a020d1b6.

This also cleans up settings a bit

Also check for (this == &other) before locking mutexes.

Also removed 2 unused functions.

Also clean up some related things.

Protocol version bump.

Catch some error situations when mod used without thinking about it