N3template operation Retraction
Created by: VeljkoMaksimovic
Tested this manually, and it seems to work. Added few tests, but few more are needed.
Questions: For now, both n3TextAdditions and n3TextRetraction property cardinalities are set to min:0, max:1. That allows to have n3Template that has no addition statements, nor retraction statements, which should not be valid. Not sure how to set "collective cardinality" on those two properties to be min:1