IN_UpdateAxis (for nice handling of axis updates, especially relative
motion for mice) and IN_Binding_HandleEvent because registering an event
handler blocks qwaq's internall call to IN_Binding_HandleEvent.
With some hacks that are not included (plan on handling events and
contexts properly), button inputs, including using listeners, are
working nicely: my little game is working again. While the trampoline
code was a bit repetitive (and I do want to clean that up), connecting
button listeners directly to Ruamoko instance methods proved to be quite
nice.
