vo_opengl: avoid texture arrays for compatibility with Intel low quality crap

Commit a0b43a1 changed textures to an array, because additional
per-texture information was needed and managing this as array is more
elegant. This broke playback on Windows with Intel drivers (window
shows green video, even though subtitles/OSD work correctly). So change
it back to make it work again.

Affected driver: Intel(R) HD Graphics 3000 9.17.10.2932
Merge branch 'master' into low_quality_intel_crap

Conflicts:
	video/out/gl_video_shaders.glsl
	video/out/vo_opengl.c
Fix building with --disable-libass

Obscure corner case, but in theory we support this.
configure: link with -lrt

In order to use clock_gettime() (which we need for use with
pthread_cond_timedwait()), most glibc versions need to link with -lrt.
configure: fix previous commit

This doesn't help if -pthread is omitted. (Apparently, glibc 2.17, on
which I tested the previous commit, doesn't require -lpthread in order
to use pthreads either.)
stream_radio: fix build

This was accidentally broken with 37c5c11 and has been nroken for
5 months.

Does anyone (want to) use this at all?
sub: Do not use deprecated “Sans” fontconfig alias
stream/tv: remove unused dshow-specific options
manpage: proofread and fix formatting
Merge remote-tracking branch 'origin/low_quality_intel_crap'

Conflicts:
	video/out/gl_video_shaders.glsl
configure: make zlib non-optional

This is needed by demux_mkv to decode files with compressed tracks.

Requested by nikoli.
input: allow binding multiple commands to a key

Separate the commands with ';'.
cache: fix compilation without posix timers

This is a regression caused by 854303a. This commit removed the include of
`sys/time.h` which was included in `cache.c` through a chain of recurvive
includes.
input: actually copy sub commands

This was missing from the previous commit. It worked by luck, because
the sub-commands weren't freed either (as long as the original command
was around), but this is proper.

Also, set the original string for command lists (needed for input-test
only).
command: add screenshot_to_file command
configure: fix oversight in log message
Merge branch 'master' into remove_old_demuxers

Conflicts:
	DOCS/man/en/changes.rst
	DOCS/man/en/options.rst
options: remove --ignore-start

This was used only with demux_avi.
demux: remove some more minor unused things
audio: remove decoder input buffer

This was unused.