Please add support for option grouping #605
Description
It would be awesome if there was a way to group options under subheadings, either for topically grouping options, or for showing which options are true when the program is operating in one of several different modes.
Probably the best way to do this using the current declarative syntax is to add an int[] group() default {} to the annotation interface, which would then give you the ability to say group = 3 or group = {1, 3} in an annotation. Group 0 would appear at the top, before any subheadings, and if there are any options belonging to groups 1 or above, those should be listed, grouped, below that.
You just need a way to specify subheadings for the groups. This could be done with the JCommander builder.