Implement character stats
Implement database storage of malikania stats.
- Add specifications docs for stats
- Update database UML
- Update character class
Server: implement new stats for character, closes #761 @2h
Each character no longer have a global level integer. Instead, separate each
stat with a different level, factor and experience which define the current stat
level, the desired partition of experience (from 100%) for this stat and the
current experience respectively.