! fixed bug in AuthorSystemContent model's getUnitByUUID()
+ added context info removal function to Unit model
# in formatSelections: made formatUnitIcons() more compact, self-contained and generically usable
# simplified loadUnit() in unitController, applying new functions formatUnitIcons() and addMetaDataToUnit()
- removed activateFunctionalities() and activateContextConfirmation()
# moved contextTab-specific event handlers from generalTabController to contextTabController
# replaced returnArray from checkInformation() with object
# replaced value of "id" in array_multiSelectionContextInfos (multiple infos of same type possible)
TODO: multiContextSelection still troublesome with new kind of IDs, needs to be revised!
TODO: compactify "all" or "one" design rendering code