Bleeding: create Requirement API.

IT IS NOT WORKING for now.

It WILL be work by jar files in /plugins/WHeroesAddon/modules/, I
planing 3 types of modules:
* Requirement module - for requirement to upgrade/lowering/unlocking
skills in skilltrees.
* SkillTree module - for compatibility with OTHER plugins than Heroes.
* Party module - for advanced parties fully compatible with x plugin.

I also change a lot of minor changes, I have resigned from lang messages
in console. I've changed instances, refences.