Fix a couple cases of lost text field focus after an edit, including
focusing of the Title field after using New Item when a field is already
being edited and has a changed value.
Also, in tests, select My Library and wait for items to load when using
the loadZoteroPane() support function. We could add a parameter to skip
that or move it to a separate function, but the code to detect it is a
bit convoluted and it's a prerequisite for many tests, so it's handy to
have a function for it.
