fixed constructors
removed unused variable "usedCorrections"
removed not used variable "muon_scale_factor_systematic_"
added break instructions in the default case
Fixed adding an integer to a strin (why was that working in the first place?)
The correct way to check a null pointer is !ptr not ptr != 0
simplified comparison so some compilers do not get confused
Merge pull request #105 from kreczko/fix-warnings

Fixing some compilation warnings