Merge pull request #1039 from dalkon/master

Add onGainSkillTries
Performance improvements & const-correctness
Fix bug with previous commit
Const-correctness & removal of const_casts
Use final/override and remove unnecessary virtual specifiers
Update .travis.yml to use clang and newer g++ version
Remove clang from .travis.yml
Use emplace for map insertions
Use emplace for map insertion
std::move eventDesc
Fix bug with vocation gainCap

Fixes #1041
Remove unnecessary virtual specifiers