FConfigLib

A lot of breaking changes occurred in this version. So mods that used previous versions of FConfigLib would likely break(not like there are any right now). In the future, I would try to make this mod as backwards compatible as possible(starting from 1.1.0).

• Some access modifiers have been changed
  
• The way config fixers are registered and applied has been changed
  
• Added config validators, they can be applied with ConfigValidators annotation
  
• Added support for mixin-based configuration via @MixinOption and MixinConfigHelper
• Added Sl4j Logger Wrapper
• Lots of refactoring