Merge some of @twostars changes
Project64: Started cleaning up the plugin system (now deriving from a base CPlugin class).
See https://github.com/twostars/project64/commit/bf4c108ce2734ed72c787370f5abb4155418c447
[~]Fix up previous commit, git said it added files when it didnt... grrrrrrr
Merge other commit of twostars work on the plugin system
@twostars Project64: Plugins loaded on demand are now fully initialised, for consistency with certain plugin expectations (ensures settings and such are loaded).

https://github.com/twostars/project64/commit/ec3b329908f77389b0138355a2f4a35e28bcb766
[+]Add SFML library, where going to be using this for netplay