This adds a new dependency with libfuildsynth. MIDI support
is built by default, but can be disabled if not desired.
All RTP songs should work well, but there are known problems
with other files (see README). Also, the pitch shift implementation
is somewhat poor and doesn't match RMXP (at least subjectively).
A soundfont is not included and must be provided by
the user themself.
Performance can still be crudely measured by turning off
the framelimit and observing the FPS count. For everything
else, there's always callgrind / apitrace.
GL entrypoint resolution is now done manually. This has a couple
immediate benefits, such as not having to retrieve hundreds of
functions pointers that we'll never use. It's also nice to have
an exact overview of all the entrypoints used by mkxp.
This change allows mkxp to run fine with core contexts, not sure
how relevant that is going to be in the future.
What's noteworthy is that _all_ entrypoints, even the ones core
in 1.1 and guaranteed to be in every libGL, are resolved
dynamically.
This has the added benefit of not having to link directly against
libGL anymore, which also cleans up the output of `ldd` quite
a bit (SDL2 loads most system deps dynamically at runtime).
GL headers are still required at build time.