[IP] Show "busy" status

[sebastian-meyer]

On several occasions requests in Goobi.Production take some time before giving feedback to the user. Currently the only way to tell if a request is currently been processed is looking at the browser's "loading" status. Instead Goobi.Production should give immediate feedback to the user and show some kind of loading bar or status icon while disabling the GUI to prevent multiple requests at the same time.

[matthias-ronge]

A reimplementation of the task manager along with the possibility to perform DMS exports as long running tasks was developed as #166 and merged as #181. (See #179, too.) This will be part of the release known as feature-zm.

Other functions taking an inordinate amount of time may be made asynchronous by basing them on the new class de.sub.goobi.helper.tasks.EmptyTask, making their progress controlable by the long running task manager.

[matthias-ronge]

I think that this general development request from the Install Party, which was documented with this ticket, was taken into account with the responsive design, which is available with current 3.x and up.