Allocating a vector for the hundreds of small files and only reading
64k at a time was a bottleneck on systems that were not I/O bound.

If the elevated user was a different user account, the updater would
look in the wrong user's appdata for the manifest and fail.

In rare cases, "runas" would somehow launch the updater as a non-admin user
again, resulting in a loop where the updater constantly spawns processes.
Fixes https://github.com/obsproject/obs-studio/issues/2984

UI: Update NSIS installer script

This would cause meaningless "Service '' not found" log entries.

If replay buffer hotkey isn't set, this would cause an error to be
logged due to a null string.

cmake: Update Windows SDK check to 19041

This brings the script in the repo up to date with what is being
used to generate release builds for OBS Studio on Windows, as
well as fixing up a few issues.

libobs-winrt: Require Windows 10 SDK 19041

This will prevent compiling without WGC cursor toggle support.

rtmp-services: Add Mixcloud service

If an image source isn't visible there is no point polling for changes
during the time it's hidden as no one will see them. Should the image
be on unreachable media such as an unavailable network share, this
check would cause the graphics thread to periodically stall trying to
detect changes of a non-visible image source.

If the image is modified while it's hidden, the updated file will now
be loaded as soon as the source is made visible - the update timer
intentionally ticks up while hidden.

Partially fixes some of the behavior described in
https://github.com/obsproject/obs-studio/issues/3007, a full fix
likely requires significant changes to support OS-specific file change
notification APIs.

This reverts commit 636f0bfd, reversing
changes made to b9ea45e4.

obs-qsv11: Simplify QSV settings in UI and Enable AVC VDEnc on ICL+ 

libobs: Fix os_get_executable_path_ptr on Linux

libobs: Use correct data pointer for hotkey pair

Terminate a non-terminated string generated by readlink()
to pass to dirname() that needs terminated string as a parameter.

docs: Remove Doxyfile

docs: Remove Doxygen

CI: Improve formatcode.sh efficiency

Combine MMBRC and CQM parameters into a subjective video
enhancement box

Batch files into clang-format to prevent needless processes. Now its
twice as fast in real time and uses 4x less resources. The old
implementation is also slower (but pretty close to) running a single
invocation of clang-format on all files.

before
time ./formatcode.sh
real	0m3.860s
user	0m20.975s
sys	0m6.694s

after
time ./formatcode.sh
real	0m1.486s
user	0m5.426s
sys	0m0.203s

UI: Set 8 x 8 as minimum selectable resolution

Since libobs internally rounds to various powers of 2 to support SSE
functions, resolutions that are too low can get rounded to zero. libobs
will fail to startup with a zero resolution, so if a user accidentally
entered anything that rounded to zero OBS would become unusable without
manual fixing by editing the profile .ini.

UI: Theme case fix

All strings were treated as partial matches before, which caused a
false positive with any executable beginning with "time", notably
affecting the game "Timelie" which used Timelie.exe.

This isn't editable by the user, so it doesn't make sense to show it.

The files on disk are lower-case but QSS refrences them in
upper-case. Windows doesn't report errors as the platform isn't case
sensitive. Error messages are generated and icons not to render on
case sensitive platforms such as Linux and Mac

CI: Require VLC in CI builds, Fix VLC in CI

cmake: Fix warnings and normalize variables/errors

Previously VLC was downloaded but was skipped since it could not be
found. This sets the VLCPath to ensure it is found.

As of 3.17 using find_package_handle_standard_args checks that the name
of the FindXXX file and the first argument are the same case.

Some modules used non-standard variables or the old singular variables
instead of plurals. This normalizes variable usage to the new-style.

Some CMakeLists.txt did custom error checking instead of propagating
find_package errors. These were changes to call find_package with
REQUIRED or without QUIET where needed and shortens the custom status
messages. This helps users who want to enable that functionality see
what precisely wasnt found.