Makes libtsm a static library rather than dynamic so that it doesn't
have to be installed as a system library on the user's operating system.
Also updates SConstruct to work on more operating systems other than
just NixOS. Adds a number of docker files for building the library on
various distributions (NixOS, Arch Linux, Ubuntu).
Uses a fork of godot-cpp with an updated godot_headers submodule that
includes godotengine/godot_headers#76. We should go back to tracking
https://github.com/godotengine/godot-cpp once the submodule has
been updated in that repo.
