lavc/srtenc: use bprint for text buffers.

Fix trac ticket #3120.
doc/ffserver: remove more mentions to LAME and build
doc/ffserver: add "Detailed description" chapter

Also move FFM section up in the file, and rename it.
ffserver: print error code description in case of write_header() failure

Improve feedback.
doc/ffserver: clarify that note in NoDaemon option documentation
doc/ffserver: clarify documentation for Feed MaxFileSize option
version.sh: make it independant of version.h file name

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'cigaes/master'

* cigaes/master:
  lavc/srtenc: use bprint for text buffers.

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