Apply preroll on virtual tuners when the same multiplex is in use.

Previously, if any tuner in the same input group was already busy,
preroll would not be applied.  Now, if the recording on the other
input is on the same multiplex as the new recording, preroll will be
applied.

Refs #12023

(cherry picked from commit 11e65dfd38ca419b2157f0dbaa19f965647f648c)
MythMusic: add a 'First' resume mode and make 'Off' never resume

This fixes the resume playback feature so that 'Off' never starts playback and
adds a new 'First' mode which starts at the first track in the active playlist.

'Track' and 'Exact' modes remain the same and resume playback at the start of
the track or exact position within the track that was playing when MythMusic
was last exited.

(cherry picked from commit 385011e307c2d5f9d5d6a65663143f27189d1b17)
MythMusic: missed a git add in [385011e307c]

(cherry picked from commit 632c4f875a081dd37d3ed2d49e0722293d2146e8)
MythCenter-wide: fix some clipping on the music playlist editor

When using the Qt painter the time text was being clipped in the small info
panel.

(cherry picked from commit da505d91987e2d3a832288038510971d31c3c4e0)
MythCenter-wide: fix some clipping on the music playlist editor

When using the Qt painter the playlist progress bar appeared to not be
updating because it was being clipped.

(cherry picked from commit e7a9bd0f4d32215f4cf5d26f01244dec42e44249)
MythCenter-wide: fix some clipping on the playlist editor screen

(cherry picked from commit a75cd556aaa602d5e16c4f8e001de9e5a7e669a2)
H264Parser::decode_Header: pic_order_present_flag is not required, so don't
insist on it.

(cherry picked from commit faf7487bd3db2f01d273e1bd7a44cf64f7762181)
DTVRecorder::FindH264Keyframes: Only account for Adaptation Field Control
Offset if payloadStart is set.

(cherry picked from commit 6c6c0cbd4d95957c107e0e7e37b6b4cf70b04de5)