application, main-toolbar: Rename "app.gear-menu" as "app.preview-menu"
There hasn't been a gear since commit 1d3532dd and 3.15.2, and
the icon was changed again in commit f284aa3c when dropping
the application menu. Therefore, it's better to use a name that
describes the menu's purpose and not how the icon looks.
16 minutes and 22 seconds
(queued for 1 second)