Improve transcript navigation, close popover on "Escape", etc.

[eweitz]

This polishes popovers, transcript menus, and protein diagrams in the Gene Leads kit.

Robust transcript navigation

Before, in a given gene annotation tooltip / popover, clicking the up and down arrows in the transcript menu would go to a different transcript, but not necessarily the next or previous. Now it does. Also, layout no longer shifts due to unusual transcript types (e.g. nonsense mediated decay) nor due to some transcripts having topology features and some not.

This means users can rapidly iterate through a gene to get a quick overview of transcript diversity.

Here's how it looks:

Improved_transcript_navigation_LDLR__Ideogram_2023-08-07.mov

Refined popovers and protein colors

Also, popover overcrowding is mitigated, so e.g. you'll be able to mouse into detail for BRCA2 without inadvertently popping up the nearby annotation for RAD51 due to a 1-2 pixel underlap. And you can dismiss popovers by pressing the "Escape" key, as is conventional in most UIs, rather than needing to mouse out and wait 1-2 seconds.

Finally, colors have been further refined for protein features, so you can more easily assess similarity within and between genes at a glance.