tests/synctest.py: Modify multiplex file

Make it have the same meaning as with the previous
multiplex system (9 variants, loop and sync parameters
with short, medium and long variants).

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.core.output: Introduce Paginator class for cleaner 'q' handling

In avocado, we use 'less' for a paginator. When one presses
'q' in the paginator, an IOError is raised (the subprocess
opened with os.popen has just quit), so let's introduce a
Paginator class, that can handle cleanly 'q' without asking
API users to handle the exception themselves.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>