Anchor overlap prevention

[adammertel]

There should be some check of such unwelcome overlap only because of text selection precision. I.e. the anchor of a child should attach inside the parent if text selection leads all the way up to the end of parent, if I'm being clear. I.e. it is allowed, but the Annotator should not contribute to creating these situations just because they are allowed.

the same issue applies to all anchors, not only T anchors. And it also applies to the anchor beginning, to create overlap only when absolutely requested - in case of same character token, Annotator should attach appropriately - inside if start anchor of entity2 is after the start anchor of entity1 (creating "subordinate/child anchor", outside if start anchor of entity2 is before the start of entity2 (creating "superordinate/parent" anchor).