Modification TerminusLocalization enum was easier to use

[acesnik]

The new switch-case based on exact string matching is much easier to mess up than an enum with several constant values.

https://github.com/smith-chem-wisc/mzLib/blob/master/Proteomics/Modifications/Modification.cs#L98

[acesnik]

I'm having to copy-paste from mzLib code to get it right, which shouldn't be necessary.

[rmillikin]

👍