TrackChanges: Bugs with editing content

Problems:

• Whitespace is deleted, but really deleted and not just tracked as deleted. (not reproducable so far)
• User A inserts some content. User B deletes one of these characters by using BACKSPACE. => The cursor is placed on the right side of the deleted character, not on the left.
• Select everything in the target (CTRL+A) and then use CTRL+. to get the source: in some cases, this leads to an error (for example #113 in simple-en-de-TEST => check if INS-Nodes already exist or so...)
• At the beginning of an INS, the same user selects multiple characters and then presses a key: the new character does not get the INS.
• User selects text and internal tag behind the text and then presses e.g. "d":
  • [text<1>]<2><3> => <del>text<1></del>d<2><3> = ok
  • [text<1><2>]<3> => <del>text<1><2></del><3>d = NOT ok

• Delete some existing content. Then reset the segment to the initial content. => Sometimes only a part of the then replaced content is markes as deleted. => no longer reproducible after TRANSLATE-1770