keyboard shortcuts

[stephenrparsons]

Must be compatible with existing OpenSeadragon shortcuts. We can either override those, or (preferred) add our own that do not interfere with the existing.

[stephenrparsons]

For the image set navigation shortcuts, we first need to do #9 to have JSONs to work with, and then #7 to have navigation functions to move in between images. the keyboard shortcuts can then simply call the existing navigation functions

[stephenrparsons]

once these are finalized they need to be made clear in the interface so the user can figure them out

[stephenrparsons]

Our keyboard shortcuts/controls:

shift+scroll: resize clipping region
c:            alternate clipping region between circle/square
i/k:          increment/decrement secondary layer index
l/j:          increment/decrement primary layer index
m/n:          increment/decrement page index

OpenSeadragon builtin keyboard shortcuts (not overridden by us, still work): https://openseadragon.github.io/examples/ui-keyboard-navigation/

Closing #6.