1. OPTIND value was not computed correctly when the argument was part of the
option string (i.e. for "l:" "-l 1" was working "-l1" was not). (PR/2505).
2. OPTARG was not being unset in case of errors [in the non POSIX error case].
3. optvar could be set to random values.
4. Option string starting with a : was not treated specially as POSIX
specifies (if the option string starts with a :, then there is no
error printed when there are missing option arguments or illegal options,
and OPTARG and optvar are being set specially).
5. Implemented getopts "opts" optvar [arg]. The optional argument case
was not implemented.
To do:
- what does Posix say about resetting the getopts state? Bash does it
by setting OPTIND=0; is that correct? Should we be doing the same thing?
- should we be using getopt(3) for everything internal to the shell? Is that
feasible because we might need to handle multiple invocations at once.