Make Mojo::IOLoop::one_tick die on recursion

[kraih]

Recently i've seen more and more applications abuse Mojo::IOLoop::one_tick to recurse back into the event loop and emulate blocking behaviour while waiting for events. This does of course not really work as soon as there is any real load on the server and will make applications crash in very unexpected ways.

Therefore i believe we should just not allow Mojo::Reactor::Poll::one_tick and Mojo::Reactor::EV::one_tick to recurse, and instead die right away if it is ever attempted.