Incorporate SVG objects on top of openseadragon

[iamyle0710]

This pull request adds the feature of incorporating SVG objects on top of openseadragon-viewer and fixes SVG rendering problem on different browsers.

Update features ( related to issue #1779)

• incorporate and parse annotations from SVG files
• add a navigation sidebar for users to turn on/off overlay
• user can toggle the display of each annotation object
• user can navigate to annotations from sidebar to openseadragon, and vice versa.

Fix SVG issues shown on different browsers ( related to issue #1814):

• fix not able to render SVG objects properly on Safari
• fix not able to detect mouse events from SVG on Firefox

[vipul-21]

@iamyle0710 Is this PR still valid or should I create a new PR from the branch svg-on-tif ?