moved skills to a new 'constants' module
Have a hook setup that checks a table whenever a player digs a node. If
the table has a node registered the nodes experience is applied to the
player's skills. If enough experience is accumulated their skill rank
goes up by one.
Updated README with current commands in dev. When a player gains a level
in a skill that skill's stats are persisted to the database.
Renamed `mmoplayer.lua` to `entities.lua`.
* added a new function `save_skills` to db.lua
* trying out busted for tests
* added settings.lua to consolidate all minetest config options
* added logger.lua that essentially wraps the minetest.log function
* renamed mmoplayers.lua to entities.lua
* updated README with some configuration options
Tweaked the existing database calls and added tests for each one.