Account selection, keyboard shortcuts, UI updates, accessibility

[austencm]

There's a lot in here...hopefully the commits are clear enough.

Basically:

• Made options page nicer
• Quick account-switching feature for users with multiple accounts
• Keyboard shortcuts: Alt-D to activate, number keys to switch accounts, D/S/P/A/F keys to create each doc type while the menu is open, up/down arrows to move between links
• Added a google drive link in the footer
• Made the icon a little cleaner