Shortcut that will work on Mac (#308)

[finanalyst]

• Mac and JS do not work consistently, so testing for altKey in JS does not activate the ALT-L type shortcuts.
• Changing for Command-L breaks other shortcuts
• CTRL-L type shortcuts are widely used for other functions, so need to be avoided
• Single character shortcuts can be implemented, but break search box entry
• / is a Firefox / Google shortcut.
• \ seems to be a compromise and has the single function of moving focus to the search entry box. Once the box has focus, \ then functions as a letter.

[finanalyst]

This can be tested on new-raku test deployment

[finanalyst]

closing this PR as superceded by #337