add dominance plot as a diagnostic for the matching

[wxwx1993]

@jennyjyounglee, developed a dominance plot tool as the diagnostic for the matching. It is useful to be an enhancement.
https://github.com/jennyjyounglee/metagam

[Naeemkh]

@wxwx1993, please add more details for this feature.

[Naeemkh]

@wxwx1993, @jennyjyounglee, please point me to the exact code.