DOCS/encoding: make "What does not work yet" a proper RST section
lua: add mp.unregister_event() function

Someone requested this... I think.
lua: give more control over timers

Now they can be paused and resumed.

Since pausing and disabling the timer is essentially the same underlying
operation, we also just provide one method for it.

mp.cancel_timer probably still works, but I'm considering this
deprecated, and it's removed from the manpage. (We didn't have a release
with this function yet, so no formal deprecation.)
remove redundant/outdated line from encodeing.rst:"what works"
vo_vdpau: more debugging output

Might help to debug certain problems with Mesa.
video: Add BT.2020-NCL colorspace and transfer function

Source: http://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.2020-0-201208-I!!PDF-E.pdf
video: Add support for non-BT.709 primaries

This add support for reading primary information from lavc, categorized
into BT.601-525, BT.601-625, BT.709 and BT.2020; and passes it on to the
vo. In vo_opengl, we always generate the 3dlut against the wider BT.2020
and transform our source into this colorspace in the shader.
options: Expose --primaries to the user
video: Support BT.2020 constant luminance system
video: Generate an accurate CMS matrix instead of hard-coding

This also avoids an extra matrix multiplication when using :srgb, making
that path both more efficient and also eliminating more hard-coded
values.

In addition, the previously hard-coded XYZ to RGB matrix will be
dynamically generated.
video: Better support for XYZ input

With this change, XYZ input is directly converted to the output
colorspace wherever possible, and to the colorspace specified by the
tags and/or --primaries option, otherwise.

This commit also restructures some of the CMS code in gl_video.c to
hopefully make it clearer which decision is being done where and why.
video: Refactor rendering intent for DCP XYZ and :srgb

Notably, we now conform to SMPTE 428-1-2006 when decoding XYZ12 input,
and we can support rendering intents other than colorimetric when
converting between BT.709 and BT.2020, like with :srgb or :icc-profile.
video: Include better heuristics for guessing primaries

This incorporates typical vertical resolutions distinguish between
very likely 525-line and very likely 625-line content.

This behavior as well as what the primaries correspond to have been
added to the documentation.