Fix exception when dragHandlerFunc is not specified.
Supply event when dragging starts.

* Hotspot dragging (hotspot attribute draggable + dragHandler function)
* External tile loading (allows to pass a function that loads tiles)
* Accept images as parameter
* Option orientationAlignNorth - use absolute orientation values if enabled
* Add getters and setters for orientationOnByDefault
* Enable orientationSupport for android regardless of the protocol

Previously, one could generate a tile set that had the second level resolution
equal to the tile resolution, so it only had one tile per face.

This reverts commit 8c085f4055.

This reverts commit d0c38ece31.

This reverts commit cf5f4df48a.

This reverts commit b1794add89.

Fix potential XSS vulnerability

This reverts commit 6d12ef7968a484eb95802411c277260c3b867c5b, which restores
commit df4c45dd33.

This reverts commit df4c45dd33 temporarily to
push a new point release.

This fixes a silent error for iOS; WebGL texture size limit also applies to
canvas dimensions.

This is needed for iOS 13+ for device orientation mode to work.

Garner's Modern English Usage (4th ed.) recommends "webpage" over "web page."

Adding missing Dockerfile dependency

Signed-off-by: Vanessa Sochat <vsochat@stanford.edu>

Adding complete example with Dockerfile to use generate.py