Remove InterruptionEventLoop and other refactorings...

[SamWitty]

This larger draft PR is intended to facilitate discussion about the ongoing design efforts for the dynamical module. Once we reach a consensus around this next phase of design, this will be broken up into substantially smaller PRs.

[SamWitty]

@eb8680 , is this entirely subsumed by #361 and #356 ?

[eb8680]

is this entirely subsumed by #361 and #356 ?

Those PRs subsume most of the internal changes to internals and handlers, but this PR also contains some changes to the public API (notably the removal of InterruptionEventLoop) that I think are still worth doing. We should create separate issues to track those, though, since the implementation of those changes here will be made obsolete by #361.

[eb8680]

Closing in favor of #361 and follow-up PRs