Investigate feasability of allowing libmbin to load other assembly containing extension classes

[monkeyman192]

It has come up recently that it might be useful to be able to have an assembly which contains extensions to libmbin by way of exposing a set of public classes which inherit from NMSTemplate.
The main issue I can forsee is that if a modder creates an MBIN file with a custom class, we need some way for libmbin/mbincompiler to dynamically load the dll produced which contains the class defintions such that it may (de)serialize the MBIN file.