For some strange reason "-t" option was only implemented
for input files while both "-t" and "-to" were available
for use for output files. This made extracting a range from
input file inconvenient.

This patch enables -to option for input so one can do

    ffmpeg -ss 1:23:20 -to 1:27:22.3 -i myinput.mkv ...
Signed-off-by: Vitaly _Vi Shukela <vi0oss@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>