attr. calc.: added error msgs and breaks
attrcalc: added saftynet
attrcalc: added error on missing attr. type
adapted to changed api: hasattribute
added saftynet in attrcalc
attrcalc: reimplemented link following, redone getlinkedattribute
attrcalc: fixed issue with increment-use of non existing attribute
Merge branch 'master' of github.com:iut-ibk/DynaMind-BasicModules