Additional fields for participants per event

e.g. room number/name, presence of parental consent form,…

mentioned in commit 09c97ecd

mentioned in commit bdb0b01a

assigned to @nik

mentioned in commit bf9b6dd5

Surveying the fields was added. Missing:

• Display of fields in TIC-Desk and in PDFs
• Fields that are not part of the registration (like room numbers, etc.)
• Manual editing of fields

added Doing label

Fields are now shown in the persons list in TIC-Desk.

removed milestone