Add ability to switch between notes by using arrow keys on the keyboard

[qumuq-til]

When a certain note is selected in the note list it would be great to scroll/switch between them by using arrow keys on the keyboard. I have many smaller notes and need to review them quickly. Selecting one after the other with a mouse takes a lot of time and is distracting.

Currently the cursor is being immediately put into the editor section on the right whenever a note is selected, so the change would imply keeping the focus/cursor in the note list when a note is clicked and a tab key could be used then to switch into the editor.