Reasons:
- can show or hide the button text with CSS (assuming
tv-config-toolbar-text is yes).
- can have different looking buttons in the page controls versus the
view toolbar, etc
- more flexibility styling the button appearance, for example you
can change the text size compared to the icon size
- button appearance is more themeable
Fixing problems caused by c4b76ceb0b:
* We still need to initialise the saver-handler even when syncing to a
server, otherwise offline snapshots can’t be saved
* We need to override the default save template a bit further up the
stack, to avoid the server side serving the offline version of the wiki
at `/`
