readable was being called without the associated file being "consumed"
leading to a crash. Furthermore their was some misbehaving casts between
size and u16 (maybe bug in hare?). This led to the frame sizes being set
to very large incorrect values that messed up printing the list.

This changes stuff like signal::SIGWINCH -> signal::sig::WINCH and poll
now returns a poll:error instead of errors::error (it actually wraps an
rt::errno in an errors::error using errors::errno and poll::error is
actually a errors::error)