Add :stopped to opts when stopped by on_stop

[wishdev]

I would like to have the parser set a value if on_stop finds a keyword in the args. Otherwise I need to parse the first argument of ARGV in order to determine whether or not a valid command was given (in a command/subcommand scenario).

Only adds it if on_stop exists.

[Fryguy]

LGTM

[Fryguy]

Technically, this could break any existing users that may have stopped as an option. Though, I'm not sure there's any "nice" way to do this given the hash. Maybe prefix the symbol with an underscore (i.e. :_stopped)

[wishdev]

:_stopped sounds perfect to me - good catch on the possible conflict

[chessbyte]

@Fryguy @kbrock please review.

[kbrock]

LGTM

@Fryguy you good with the _stopped?