No more equals signs for options that don't take values.
Complete values for options with preset choices.
Complete --no-whatever where applicable.
Fixes#997.
The previous commit made the completion script always return non-zero, even when
a match is found. This explicitly sets the return value to zero whenever a match
is found but defaults to non-zero in case nothing is matched.
Returning a non-zero value signals to the zsh completion system that no matches
were added by the script so that it can try the user-defined matchers (e.g.
those defined with matcher-list).
Fixes#1008.
Don't use _x_arguments, as we don't support X arguments.
Get rid of -s, because we don't support multiple single-letter options
in one argument.
Add -S, because we ignore options after "--".
Completion now uses "--opt=value" instead of "--opt value". Once the
user presses space and starts a new argument, the option just
completed is out of the picture, whether or not it was given an
argument. This handles options with no arguments or optional arguments
much better; previously, completing such an option would effectively
disable completion for the next argument.
Custom completed options such as "--ao" and friends will no longer
claim to consume an extra argument.
