avtools: move media_type_string() from avprobe to cmdutils.

It will be useful outside of avprobe.
cmdutils: allow -h filter=<name> to print information about a filter.
lavfi: new interlace filter

Signed-off-by: Anton Khirnov <anton@khirnov.net>
FATE: add a test for the interlace filter

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Merge commit 'e19e8aeeaaff3d4bc8f6065764c93f0298782ac6'

* commit 'e19e8aeeaaff3d4bc8f6065764c93f0298782ac6':
  avtools: move media_type_string() from avprobe to cmdutils.

Conflicts:
	avprobe.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '921046008f5335601f9d76dc3a768eb5cd91e1b9'

* commit '921046008f5335601f9d76dc3a768eb5cd91e1b9':
  cmdutils: allow -h filter=<name> to print information about a filter.

Conflicts:
	cmdutils.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  FATE: add a test for the interlace filter
  lavfi: new interlace filter

Conflicts:
	Changelog
	configure
	doc/filters.texi
	libavfilter/Makefile
	libavfilter/allfilters.c
	tests/fate/filter.mak

Merged-by: Michael Niedermayer <michaelni@gmx.at>
vf_interlace: fix frame rate

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>