Touchscreen Swipe Navigation per Francesco Pasa

Adds touchscreen gestures (not trackpad or mouse gestures) to navigate back, forward and reload the page to Firefox.

The gestures provided only require a single finger:

- Swipe to the right to navigate back
- Swipe to the left to navigate forward
- Pull down from the top of the page to reload.

Gestures work at any position in the page, not only at the edges, making it easy to navigate when holding the device with both hands.

If you find situations where it does not work, please report it.