Previously, setup.py had been the main build process, and would
probe the system for dependencies. Now that all dependencies are
available on all platforms, and cross-compiling is done by renpy-build,
setup.py has been simplified by assuming everything is present.
(Optional probing is done using pkg-config.)
Various includes have been changed to be more canonical.
This directory contained a mix of both c/cython source code, scripts,
and build information. Now, source is in src, scripts are in scripts,
and setup.py is in the root.