Re-Add "double-Enter" to lending/returning
In the really old klausurtool, when entering the folder ids one could do a "double-Enter", i.e. entering two line breaks, to go to the next lending step. This enabled quick processing of folders since the first step can completely be done on the numpad (no switching to mouse, to tab key, or doing alt+shift+w). The next step can also be done with one hand and few movements*.
*left hand used to hold folders, right one moves across the keyboard until the imt login is required. Afterwards folders and deposit are exchanged, student can leave and deposit is entered.