Display AwesomeTTS as top-level menu on Browser

Doing it this way provides an easier visibility and also keeps other
existing code (e.g. muzzling the shortcut while in the editor) working
as-is AND does not increase the width of the window.
Documentation update for new menu location

Updates all screenshots and step-by-step instructions to show/refer to
the new location of the AwesomeTTS menu.
Keyboard accelerators for AwesomeTTS menu

Adds 'a' and 'r' keyboard accelerators for the "AwesomeTTS" menu in the
card browser.
Merge branch 'chg/browser-button-44' into develop

Moves the AwesomeTTS menu location and updates associated documentation.

Closes #44.