Add support for more than just .cs#20

For example, the way of writing plugins as DLLs would help a lot to optimize them, mainly due to the removal of a lot of reflection :

1) Direct specification of the plugin type - API function calls without Call, but directly
2) Getting rid of boxing of call arguments or constant conversion to system types (int, string).
3) Convenient plugin organization - possibility to build architecture

What I’m using at the moment: https://github.com/rube200/Oxide.Ext.DllLoader

I also attach below a screenshot of what your plugins could look like