Try to mimic a tad closer to an actual AppleTV.

Sometimes AirPlay photo isn't seen on my mac... so just in case...
Minor code clean-up. C++-ify it
Fix typo introduced in earlier commit

would have prevented airplay to work on new system
Change theme widget names to be a bit more universal

Was too focused on playing music, a legacy from originally using the miniplayer theme
Add MythNotification convenience constructors
Add support for all types of notifications via the UDP listener interface.
Add support for all type of notifications via mythutils
Full screen notification theme tweaks
Fix infinite reprocessing loop for booleans in command line parser.

This fixes the immediate issue, by allowing the parser loop to
distinguish between the two scenarios, and only attempt reprocessing if
it makes sense to.

Refs #11642

I'm leaving the ticket open, as we should not be reporting an error
prematurely when we're going to attempt reprocessing. We should probably
also accept various forms of "true" and "false" for booleans, rather
than accept no values.
Merge remote-tracking branch 'upstream/master'