Merge commit '07584eaf'

* commit '07584eaf':
  mpegts: check substreams before discarding
  Add a smooth streaming segmenter muxer
  file: Add an avoption for disabling truncating existing files on open
  img2dec: always close AVIOContexts
  rtpdec_jpeg: Error out on other unsupported type values as well
  rtpdec_jpeg: Disallow using the reserved q values
  rtpdec_jpeg: Fold the default qtables case into an existing if statement
  rtpdec_jpeg: Store and reuse old qtables for q values 128-254
  rtpdec_jpeg: Simplify the calculation of the number of qtables
  rtpdec_jpeg: Add more comments about the fields in the SOF0 section
  rtpdec_jpeg: Clarify where the subsampling magic numbers come from
  rtpdec_jpeg: Don't use a bitstream writer for the EOI marker
  rtpdec_jpeg: Don't needlessly use a bitstream writer for the header
  rtpdec_jpeg: Simplify writing of the jpeg header
  rtpdec_jpeg: Merge two if statements
  rtpdec_jpeg: Write the DHT section properly

Conflicts:
	libavformat/Makefile
	libavformat/allformats.c
	libavformat/version.h

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