Refactor Data Model - Master Skill Definitions about openmu

[sven-n]

I’m currently working on it and it seems that some more changes will be required.

1. Currently, a master skill just has a definition for level depending damage. Buffs etc. are not yet meant to have level depending effects. It will make more sense to have something general for all use cases.

2. The level depending values are calculated by some crazy formulas. We could either store the resulting values (like we do already for attack damage) or store a formula - I tend to the latter. However, then we need something to evaluate them at runtime, e.g. https://github.com/mariuszgromada/MathParser.org-mXparser

3. If we think a step further, we could even think about making formula evaluations possible within the attribute system infrastructure