MythMusic: fix a possible crash after scanning for music

MusicMetadata::getSongAt() can return NULL so guard against that.
Fixes #12200. Thanks to JYA for finding the problem.
MythArchive: don't needlessly copy videos before processing

If a video can be found on the local file system pass that file name to the
mythburn.py rather than always passing a myth:// URL which will always cause
the script to do a file copy before processing the file.

Fixes #12291. Thanks to John Pilkington for testing.
Fix the ability to disable the frontend idle timer
AirPlay: Fix iOS 8 not seeing video device.

This is done by advertising support for mirror service (which we don't).
mythtranscode: Prevent double-free

Not the best way to solve the problem, but it works...

Fixes #12228
Fix memory corruption issue in mythtranscode. Refs #12228
Fix a number of mis-uses of AVPacket in mythtranscode

Fixes some leaks, memory issues and segfaults.

We still mis-use AVPacket, but this at least lets lossless transcodes
with cut lists run to completion. Better fixes may come later when we
have more time to work on them.

Fixes #12280
Treat the failure to create the database object as a fatal error.
More lossless mythtranscode fixes

Lossless (mpeg2) transcodes in master now seem to work perfectly on every file
I've tried included files which have always failed to
transcode. Feedback to the forum, irc, mythtv-dev or mythtv-users list
would be appreciated. I'd like to know whether this resolves long
standing lossless mpeg2 transcoding failures for anyone else. I make no
promise to fix unresolved issues, but it would be good to know if
things have moved in the right direction.

Fixes #12280
disable metadata unit test for now
use type and verify it against Type()

silence a compiler warning
UPnP: Fix silly mistake picked up by cppcheck
silence cppcheck by not updating state after the last pixel
initialize all members in the constructor

Though I wonder if setting m_run(true) isn't a bit early, when we
could set it in Run().
DataDirectProcessor: Add logging when file opens fail

Fixes #12251.

Signed-off-by: Paul Harrison <pharrison@mythtv.org>
DataDirectProcessor: Use random temporary filenames for downloads

Fixes #12253.

Signed-off-by: Paul Harrison <pharrison@mythtv.org>
reorder initialization to silence the compiler, too
call the superclass method exit explicitly to silence cppcheck
avoid going uint_8 -> unsigned int -> uint8_t

silence compiler warnings about going narrowing conversion
YUV offsets are int only in VideoFrame

silence warning about narrowing conversing when ptrdiff_t != int