Adds some more tests and tries to solve some code bugs.
Adds some more tests and tries to solve some code bugs.

A new variance parameter was added to assertPointsEquals function.

Variance value was set on loopingTestHelper function (1e-15).

The following tests were modified to execute tests on flipped viewport:
* 'panBy'
* 'panTo'
* 'zoomBy with ref point'

openseadragon/openseadragon,openseadragon/openseadragon