Add "refresh" button

After not using Specter for a while, and then returning to the window, I often get this error message in red at the top middle:

`"Session expired. Please refresh and try again"`

And I guess the solution is to either:
Right click->Reload
or
View->Reload

However, neither of those options are very intuitive to find. It would be nice to have a simple refresh circle button, maybe in the upper right corner next to the view toggles and settings button.

No file or test is named. Start by locating the view toggles, settings button, and the code that displays the session-expired message; check how reload is currently triggered. Done means a visible refresh button appears beside those controls and performs the expected reload.

Written by the indexing model from the issue text.