Migrate Game Dependencies to Extern Top-Level Directory #571
Description
At the project structure level - we shouldn't really have an include directory at all at the moment since the BfBB decomp isn't a library for other projects to import. The Melee decomp project follows the C++ project standard of having external dependencies contained in a extern/external folder and then each dependency is a subdirectory under that, for example.
We should refactor the project such that all external dependencies (Dolphin SDK, Renderware SDK, Bink, PowerPC EABI, etc.) are contained within
a top-level directory extern. This will require making lots of small changes to compiler paths and such.
Some relevant links
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1204r0.html
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines