Enabling pinch with any number of fingers

[mehdi-cit]

Hello,
By default, marzipano doesn't allow for multi finger dragging/rotating as seen here:
#367
In my use case. I need to allow the user to drag/rotate the picture when using one, two or more fingers. I.e. no matter how many fingers the user is able to do the same thing.
As of version "marzipano": "0.10.2", one can use two fingers when passing some "pinch" option! However, this has two limitations when it comes to my use case. First, it won't work when using more than two fingers. Second, if using a single finger it has no effect on the image and the scrolling happens (or is supposed to happen) on the containing page/widget.
This is a PR for allowing such thing.

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[mehdi-cit]

@googlebot I signed it!

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[mehdi-cit]

@googlebot I fixed it.

[hemanthere]

This is a great addition, fits perfectly into our use-case where we want users to interact with our product on big screens in our stores. Would be great to see PR being approved.

[mehdi-cit]

Please, let us know if this PR is not going to be considered and why!
Maybe I should create a fork (we really need multi-touch)

[HemantKumarSharma2]

@tjgq Can you please approve and merge this Pull request, if everything is fine with the PR? I would really appreciate it.