Make lib199 periodic methods run asynchronously

[CoolSpy3]

To be tested

[brettle]

Changes seem fine but I recommend waiting until post-competition to avoid introducing new issues at this point. If there is an issue with thread-safety in the rev code, it may only occur occasionally and would thus be very difficult to debug. I also recommend reaching out to rev to find out if their code is supposed to be thread safe (unless you see that documented somewhere).

[CoolSpy3]

I also recommend reaching out to rev to find out if their code is supposed to be thread safe (unless you see that documented somewhere).

I emailed Rev, and they report that "Regarding whether REVLib is thread-safe, it is intended to be thread-safe, yes!"

[ProfessorAtomicManiac]

I'm unfamiliar with how multithreading works so at the moment I'm not sure what to comment on. I trust that Ryan got everything down :)