Properly declare shims for macOS.

Configure environment for Linux.

Server runs ok, the game runs but with no window...

Unify variables across the project.

Fix CMake lib dependencies for crypto/SSL. Also ensure websockets work on macOS for both client and server.

Remove symlinks and make codebase use common modules instead.

Rename files in order to prepare for extraction for publishing
subsystems independently.

Put input and video subsystems into their own directories.