[mythtv] Manual Job Scheduling for Playlists

[Brad Benson]

Since the addition of the new job queue and user jobs in 0.17 a few
folks on the -user list asked for a way to manually start a user job
from the frontend (similar to the existing code to start
transcoding/commflagging).  This seemed pretty trivial so I went ahead
and created a patch for that which has since been committed to cvs by
Chris Pinkham.

While I was doing that I noticed that there's no way to manually start
any type of jobs for an entire playlist and thought this seemed like a
pretty useful feature.  I've done a little work on adding this manual
job support for playlists, but thought I should post here and get some
thoughts from others on exactly how this should work before I get too
deep into it.  I've discussed this a bit with Chris and here's what
I've currently got for how it should work:

I'll use commflagging as a sample job to describe the functionality,
but this would, obviously, apply equally for each job type.

when the 'job options' menu is displayed for a playlist, the user
would see a 'start flagging' button if any of the recordings in the
playlist do not currently have a commflagging job either queued or
already running
selecting the start button would then queue a commflagging job for all
recordings in the playlist that don't already have that job queued or
running (any recordings with the job already queued would be ignored
as this would be a duplicate request)

if all recordings in the playlist already have a commflagging job
queued or running then the user would see a 'stop flagging' button
selecting the stop button would send a stop command for any
commflagging job that is queued or running for any recording in the
playlist

This seems pretty straightforward to me, but if there's something I'm
missing or if anyone can think of a reason why we might not want to
add this feature please let me know.

Brad