Remove incorrect selection of DST offset.

This makes the default offsettzinfo just use the standard timezone
offset from the time module, rather than incorrectly using the existence
of a DST offset as indication that the system is currently in DST.
(cherry picked from commit 4dd0bf8014bf8261c8ed347517ef8197ac7f942e)
Allow posixtzinfo to use the TZ environmental variable.

This adds a check for the TZ environmental variable, and uses that to
define the local timezone if available, rather than always using
/etc/localtime. This resolves an issue on Debian-based systems that
always use the TZ variable, rather than defining the localtime file.
(cherry picked from commit 0bffe0648d7b19ff2b2ca289699982c23a12f455)
Fix typo in tmdb3.py that returns invalid crew IDs.
(cherry picked from commit f4bb17ff2b964c001df376337aa29323615cf790)
Fix an issue with keyframe positions produced by mythcommflag --rebuild.

The seeking code in DecoderBase assumes there is a keyframe at frame
0, otherwise it shifts all keyframe numbers by the value of the first
keyframe number in the map.  This causes problems for recordings with
variable keyframe distances.  To correct this, make sure mythcommflag
--rebuild creates an explicit entry for frame 0.

Note: this does not fix the issue of mythcommflag --rebuild adding
bogus keyframes to the seektable for h.264 recordings.

Cherry-picked from a small part of
49dbed5be0729b04a5f0fd0426a32fceb2dd7935 .
Bump MDM::downloadNow() timeout up to 60 seconds.

The previous 10-second timeout was causing issues when trying to
download large lineups from Schedules Direct. This commit bumps
the downloadNow() timeout to 60 seconds.  This is a blocking call,
so if the caller doesn't want to potentially block for that long,
they should be use one of the non-blocking methods.

References #11287.

(cherry picked from commit afa03f27a2fb442800f148fb28da1f7585a2f02f)
Configure the h.264 parser to identify only IDR keyframes.

This makes keyframes identified by "mythcommflag --rebuild" and
mythtranscode much closer to reality, though there are still
discrepancies compared to the recorder and raw ffmpeg.
(cherry picked from commit 590f161b1d5ff8c7e08b0beae480ece7a185d3ab)
mythccextractor: Fix teletext subtitle duration

Previously ProcessTeletext() didn't leave one subtitle behind.  This caused the
length calculation in IngestSubtitle() to never be performed, which meant that
the length was always set to the default value 750 ms.

Fixes #11081.
(cherry picked from commit 08ad6cef707456e959b48d5e48c09929e023fc49)
(cherry picked from commit 018691f04687321f90ef2938455824065bcf674e)
mythccextractor: Skip teletext page headers
(cherry picked from commit 9519a103da6ad8dc589042fbda4fdfe4e1a2fca8)