Fix possible segfault when exiting a screen when using the Qt painter

This changes MythScreenStack::PopScreen() to call deleteLater() on the
screen rather than immediately deleting it so as to allow any keypressEvent
handlers to complete safely before the screen is deleted when control
returns to the event loop.

Fixes #11383.
(cherry picked from commit c713988707d2c795a2a2abeff817d1b187d4b3f6)
Fix bug in mythtranscodes clean-cutting mechanism

One of the clean-cut methods interacted badly with mythtranscodes
synchronisation algorithm and would sometimes cause frames from
cut segments to be kept. This commit fixes that bug

Refs #11531
MythMusic: append "\r\n" to the Authorization line in the shoutcast header

This fixes a problem with connecting to ice/shoutcast streams requiring
authentication.

Thanks to dashs on irc for finding the error.
(cherry picked from commit bbc5e9cb0df704d3cc96deffbdad2b925031f73e)
MythMusic: remove any username/password when displaying any radio stream URLs
(cherry picked from commit 324738353ef07c8dba811dea4069c7b1112c6c3e)

Conflicts:
	mythtv/libs/libmythmetadata/musicmetadata.cpp
MythMusic: fix compilation after last cherry-pick
Potentially fix segfaults on frontend startup

In nvctrl-util's GetNvidiaRates():
Initialise buf values to NULL, reduce it's size from 256 to 8 since
we're only interested in the first 8 tokens and actually check that we
parsed all 8 from the string before proceeding to use them.

While here change logging from VB_PLAYBACK to VB_GUI which makes more sense.

This may fix some frontend startup segfaults experienced by some
people since we ended up using an area of uninitialised memory in
strtol.

Coverity 746855
(cherry picked from commit 516719ad7e750a258bd2f72f79eae099f79d303b)
Pull in fix for out-of-bounds array write in xine_demux_sputext.cpp from upstream. Coverity 746831
(cherry picked from commit 70309164e52c24a69cc151d3b37036e68e45f096)
Fix fence post error in 516719a
(cherry picked from commit ec3a978eec841652993147940472c9a059c2c14b)
Merge pull request #6 from MythTV/fixes/0.26

Fixes/0.26