Unit tests for canvas drag, release, click events

Added test for canvas-drag, canvas-release, and canvas-click events
Added a mention about basic.html
Unit tests for canvas drag, release, click events
Graceful handling of IE cross-domain AJAX failures

Prior to IE 10, XmlHttpRequest cannot be used for requests to a
different origin even when the target URL's CORS headers would allow
access (see http://caniuse.com/#feat=cors).

This is easy to miss in testing if you use a single origin during
testing but have a CDN or domain-sharding for production and will break
the error handler function passed to makeAjaxRequest() if that code
assumes it can access properties on the request object.

This adds a more informative pointer to Microsoft's documentation when a
security exception is raised.
Graceful handling of cross-domain tilesource failures on IE<10

The TileSource error handling path used to raise non-obvious
"Unspecified error" exceptions on IE < 10 when configured with a URL
from a different origin (hostname or port) because the handler included
``xhr.status`` in the error message, triggering a security exception.

Now the second exception is caught and the log message will use the
original exception message instead to make the root cause more obvious.
Merge pull request #208 from acdha/ie8-ajax-error-handler-fix

Fix AJAX error reporting on IE8
Changelog for #208
Unit tests for canvas drag, release, click events
Add viewportToImageRectangle method and add support to pass a point to viewportToImageCoordinates and imageToViewportCoordinates
added support for iiif 1.1
Merge pull request #209 from msalsbery/Events-Unit-Tests

Unit tests for canvas drag, release, click events
Add comments and fix indentation
Merge pull request #212 from avandecreme/master

Add viewportToImageRectangle method
Updated changelog for #212
Changed Seajax to OpenSeadragon
MouseTracker original events in handlers

Implemented "Expose original event in handlers" (#23) for MouseTracker

Added OpenSeadragon.getElementOffset() method. Element-relative mouse
coordinates should be correct even if the element and/or page is
scrolled (#131)
MouseTracker Original Events in handlers

Comment & Formatting fixes
MouseTracker Original Events in Handlers

More formatting fixes
MouseTracker Original Events in Handlers

More formatting fixes
MouseTracker Original Events in Handlers

Bug fixes.  Event handler methods shouldn't be called directly in
theory...