All option parsing functions now match the function pointer signature through
which they are called (int f(const char *, const char *), thereby working
reliably on all platforms.
Prefix all option processing functions with opt_
Make ff* tools only accept opt_* functions taking two arguments.
The distinction between functions with one and two arguments is quite
pointless. Simplify parse_options() code.
filters.
Currently filters are not registered, so the option will show none.
Originally committed as revision 20807 to svn://svn.ffmpeg.org/ffmpeg/trunk
