* README.gpgconf (NAME): Add info about optional arg and arg type 0.
* gpgconf-comp.c (gc_component_change_options): Parse list of
arg type 0 options.
(option_check_validity): Add new argument NEW_VALUE_NR. Perform
rigorous validity checks.
(change_options_program): Disable an option also if we have a new
value for it.
* gpgconf-comp.c (struct gc_option): Add new member new_flags.
(option_check_validity): Check OPTION->new_flags beside
OPTION->new_value. Add new argument FLAGS.
(gc_component_change_options): Support default flag correctly.
(change_options_program): Likewise.
* README.gpgconf: Revert last change. Add new flags "default",
"default desc" and "no arg desc". Add new field ARGDEF. Add new
field FLAG to backend interface.
* gpgconf-comp.c (struct gc_option): Make flags of type unsigned
long.
(gc_component_list_options): Adjust type for flags.
Add default argument field.
(retrieve_options_from_program): Use "1" as value for non-option
arguments, not "Y".
(gc_component_change_options): Read in flags from input.
* gpgconf-comp.c (hextobyte): New function.
(percent_deescape): New function.
(get_config_pathname): Percent deescape pathname if taken from
option (default) value. Use default value only if it exists and
is not empty. Use empty string otherwise. Don't include leading
quote in pathname.
(change_options_program): Percent deescape string before writing
it out.
