[mythtv] Preview images - skip commercial breaks.

[Nicholas McCoy]

Sometimes my preview images show a commercial and are therefore not
very useful.  I decided to code a patch to take advantage of the
commercial flags to avoid this.  I've attached my work so far.  Here
are some questions that came up.

1.  Is it a problem to have images changing?

The images make a nice quick reference for the user about which
episode it is.  The patch will cause the image to change when commflag
is run.  I've thought about running the code only if the preview falls
in a commercial break.  That would give less consistent selection
(some exact, some based on commercials), but would leave images
unchanged by commercial skipping unless they were in a commercial.

Another possibility is to make this behavior a configurable option.  I
don't think that is necessary though.

2.  Where should I change the code to recreate the image?

Currently, I delete the image file and the next time a preview image
is needed it reruns the code, which compensates for commercials.  I'd
like to make the update automatic.  One idea is to delete the file
when NuppelVideoPlayer::FlagCommercials is complete.  Another is to
check if the recording is commercial flagged in
PlaybackBox::getPixmap.  This second choice will require checking the
times of the image and the commercial flags somehow.

3.  How do I get MythWeb to update the images?

I deleted the image file and regenerated it by browsing it in the
frontend.  When I opened the web page it still had the old image. 
Rebooting the backend and refreshing the page didn't help.  I don't
know anything about Apache or Php so I'm completely lost on this one.

4.  Should I use NuppelVideoPlayer::commBreakMap instead of a local variable?

This could be more efficient, but I'm worried about breaking the stuff
that uses this variable.