Double tapping

[ryanmasondavies]

This would be a worthwhile addition, and could be easily achieved by calling -tap twice.

The API for calling this method should look like this:

// Tap once, wait two seconds, then tap again.
[view doubleTapWithInterval:2.0f];

// Use a default interval of, say, 0.2f seconds (this might change).
[view doubleTap];

Testing could be performed by ensuring that a gesture recogniser is triggered.