Lightbox: Added error handling in ajax call and button handling also for lightbox forms outside lightbox. Added also the possibility to ignore a form inside lightbox or a button inside lightbox form.

Include details about the url's in the VuFind.lightbox.login event so that different action can be initiated based on the values.

Don't use window.location.reload() to refresh the page because it would warn about any POST parameters (e.g. login right after changing language).

Added a login event to the lightbox to enable custom actions when a login is performed in a lightbox.

Isolate success messages from the html in lightbox first before trying to deframe it for success messages to work even if the isolation would not be successful.

Improved the clicked submit button detection to work on all platforms and cases where the form has multiple submit buttons.

- Rewrote Javascript to make better use of server-side logic
- Eliminated many server-side special cases specific to lightbox handling
- Adjusted test suite to accommodate improvements

- Replace getters with public properties for simplicity/perforamnce.

[VUFIND-1149] Don't mess up the login lightbox if the user has already logged in in another browser tab or window.