Argument searching

[Owez]

Now that most everything else is finished, argument searching (for both generally and for if only used == true) is a must

[Owez]

Either ctx.get("--argument") with this being a const fn for panics or cli_get!(ctx, --argument) which is uglier but macros are really the ideal case for this. The non-workaround would be ctx.get!(--argument) but this doesn't exist (yet)

[Owez]

Done with data and get_arg/get_cmd. A further extension to this could and should be multiple parts in data like so:

ctx.data("subcmd --argument")

Instead of the current system which is:

ctx.get_cmd("subcmd").data("--argument")