The shaders to unpack YUV information from the same texture were rather
complicated. Breaking them up into separate textures makes the shaders
much simpler, and we can remove the PRECISION_OFFSET hack.

Performance also gets a nice boost on Intel for planar textures.

Intel GPA, SetStablePowerState, Intel HD Graphics 530, 1920x1080

UYVY: 473 us -> 457 us
YUY2: 492 us -> 422 us
YVYU: 491 us -> 441 us
I420: 1637 us -> 505 us
I422: 1644 us -> 482 us
I444: 1653 us -> 504 us
NV12: 1656 us -> 369 us
Y800 (limited): 270 us -> 277 us
Y800 (full): 263 us -> 289 us
RGB (limited): 341 us -> 411 us
BGR3 (limited): 512 us -> 509 us
BGR3 (full): 527 us -> 534 us

libobs: Separate textures for YUV output, fix chroma

UI: Fix Int/Float Sliders and Spinboxes by partially reverting PR #1979

libobs: Add GPU timestamp query support

obs-scripting: Use a recursive mutex for Lua scripting

This enables stacking of Lua driven filters of the same kind without
freezing OBS Studio in place, or even crashing.

obs-scripting: Add pause scene script

UI: Fix pause button checked color with Rachni theme

UI: Remove Twitch from MultichannelWarning message

libobs: Fix stale format in async frame cache

The video format is not updated if switching between cache-compatible
formats, e.g. YUY2 and YVYU, resulting in the wrong conversion technique
being used. This change ensures the format is always up-to-date.

Due to the recent change of using FFmpeg to decode MJPEG, MJPEG was
getting included in the delayed device check.  This fixes that so that
it doesn't.  MJPEG can decode in real time.

IsEncoded is meant to be used to indicated delayed devices, such as
older Elgato devices, or Hauppauge device.  Devices that use H264 and
have a 800+ millisecond latency.  This changes the function name to
better indicate that.

Fixes FFmpeg 4.0 deprecation warnings.

Fixes hardware decoding support and updates it to FFmpeg 4.0.

This change only wraps the functionality. I have rough code to exercise
the the query functionality, but that part is not really clean enough to
submit.

This broke support for various filters, sources and encoders and should not
have been merged as it is.

The shaders to pack YUV information into the same texture were rather
complicated and suffering precision issues. Breaking them up into
separate textures makes the shaders much simpler and avoids having to
compute large integer offsets. Unfortunately, the code to handle
multiple textures is not as pleasant, but at least the NV12 rendering
path is no longer separate.

In addition, write chroma samples to "standard" offsets. For I444,
there's no difference, but I420/NV12 formats now have chroma shifted to
the left as 4:2:0 is shown in the H.264 specification.

Intel GPA, SetStablePowerState, Intel HD Graphics 530

Expect speed incrase:
I420: 844 us -> 493 us (254 us + 190 us + 274 us)
I444: 837 us -> 747 us (258 us + 276 us + 272 us)
NV12: 450 us -> 368 us (319 us + 168 us)

Expect no change:
NV12 (HW): 580 (481 us + 166 us) us -> 588 us (468 us + 247 us)
RGB: 359 us -> 387 us

Fixes https://obsproject.com/mantis/view.php?id=624
Fixes https://obsproject.com/mantis/view.php?id=1512

Optimize bicubic shader

(This also modifies the UI module)

Adds the ability for a source to monitor by default.  This is mainly
aimed at browser sources, so that they do not stop outputting audio by
default like they used to.

Add planar 4:2:2 video support; Use FFmpeg MJPEG decoder instead of DirectShow

Use bilinear filtering to reduce 16 taps to 9 for the regular path. This
works because the middle weights are always between 0 and 1, allowing
texture coordinates to be placed strategically to sample correct ratios.
I'm not sure about the undistort path, so I've left that alone.

Also remove weight normalization. I'm not seeing that make even a small
difference.

Intel HD Graphics 530, D3D11
644x478 -> 1323x1080: 1790 us -> 1279 us
1920x1080 -> 1280x720: 1301 us -> 918 us

References:
https://entropymine.com/imageworsener/bicubic/
http://vec3.ca/bicubic-filtering-in-fewer-taps/
http://developer.download.nvidia.com/books/HTML/gpugems/gpugems_ch24.html

When mixing sampling with raw loads in a shader, ending a shader with a
load would case the default sampler to become unset for OpenGL. Instead,
initialize with no sampler, and only set if there is a sampler.

UI: Add option to warn on stop recording

Measured lower CPU usage and latency than default DirectShow filter.
Tested with Logitech BRIO camera at 4K, 30 FPS.

This format has been seen when using FFmpeg MJPEG decompression.

GL support improvements

libobs: Rework RGB to YUV conversion

I think this was leftover from an abandoned approach.

UI: Improve look of adv audio control dialog