Feature/present with gesture

[raxityo]

Checklist

• [x] I've tested my changes.
• [x] I've read the Contribution Guidelines.
• [x] I've updated the documentation if necessary.

Motivation and Context

Providing SourceView is not always sufficient, especially when showing the PopMenu in iPad. This change adds the extension I described in this comment: https://github.com/CaliCastle/PopMenu/issues/14#issuecomment-432052575

[CaliCastle]

Thank you so much for contributing to PopMenu, I'm currently prepping for a trip, I'll take a look when I land in China in a few days, thanks!