[mythtv] Preview image cleanup

[Otto Kolsi]

Couple of observations related to preview images:

myth.find_orphans.pl is very handy and I'm running it weekly to spot out 
any left overs etc. However, it doesn't recognize the 'size' format of 
MythWeb's preview images. To correct this, I've added following two 
lines around line 147 in myth.find_orphans.pl:

   $seen_basename{$basename.".100x0x89.png"}++; # MythWeb thumbnail
   $seen_basename{$basename.".320x0x89.png"}++; # MythWeb thumbnail

Not sure what are all the preview image sizes that should be considered, 
a regexp based matching would be much better than this hard coded version.

Another issue is that when a recording is transcoded MPG -> NUV format, 
it looks like the xxx.mpg.png preview image is renamed (or 
deleted/recreated?) to xxx.nuv.png but the MythWeb preview images are 
left intact (xxx.mpg.100x0x89.png). This makes those files orphans..
-- 
   Otto