Ability to complete pause and resume a terminal instance

The Perl module has `teardown_term` and `setup_term` exposed in the API, the intention being to allow applications to shut down the terminal instance again to get temporary control back (for example, to run a shell), and give it back to the TickitTerm later. However, these don't actually function correctly as they're not fully wired-in to the termkey_stop / termkey_start calls.

See also
  https://rt.cpan.org/Ticket/Display.html?id=107131