interfaceio: TapIO -> ReadLoop (make more generic)
interfaceio: TapIO -> ReadLoop (make more generic)

TapIO didn't really do much that was specific to taps -- it just selects
on file-like objects and then calls a _do_rx().  So we rename it to
something more generic, and make the class itself manage its own
singletonness rather than have TapInterface do that.

MurphyMc/pox,noxrepo/pox,noxrepo/pox,MurphyMc/pox,MurphyMc/pox,noxrepo/pox,MurphyMc/pox,MurphyMc/pox,noxrepo/pox