New syntax contains an optional stream type, allowing to refer to n-th
stream of specific type.
Omitting stream number now maps all streams of the given type.
They are confusing, irregular and redundant -- -map already contains all
the information. Stream maps can now be parsed in opt_output_file().
Add a more user-friendly default behavior in case no maps are present.
Breaks -programid for now, but it never worked properly anyway. A better
solution will be written soon.
Before, it took an input and output file index, now it only takes an
input file and applies to the next output file.
Stream/chapter/program specification is now part of the option name and
the delimiter was changed from ',' to ':' to be consistent with the
similar feature for AVOptions.
