Some refactoring:

1) Moved the code for the ESP/ESM plugin handling out of the parser namespace
2) Renamed the namespace that contained the ESP/ESM plugin handling to espm

I may change it so that there's a central fileFormat namespace containing the namespaces for each on (espm, ess, etc), but we'll see.

This serves a few purposes:

1) It aids reability as the names are shorter and make more sense
2) It makes more sense with the logical grouping of things
3) It allows the functions for handling to not conflict with other functions for different files with the same parameters, return types, and names
4) It enables things to be broken apart in a more sensible manner as time goes on and more work is done on the cleanup

However, any current code needs to be changed to match the changes made to the namespace.