Add Image Map

[cygnus8929]

Add an image map similar to what is available with the Ajax-Zoom solution viewable at https://www.ajax-zoom.com/examples/example3.php.

Describe the solution you'd like
The image map can be toggled by a button in the toolbar.
The image map can be set to be visible on startup via an option.
The image map is movable by clicking-and-dragging (as is the case with the one at Ajax-Zoom).
The default location of the image map can be set via an option.

Additional context
Here is a screen shot of the image map available at Ajax-Zoom.

[fengyuanchen]

It is not useful for most people. In order to keep the library simple, this feature will not be supported.