Edge: Catch up on TrackChange-developments

Check (and add if necessary) TrackChange-handling in Microsoft's Edge:

• adding whitespace via buttons must be surrounded with INS
• are deleted images for whitespace etc. marked correctly?
• type in empty segment => after the first stop, the cursor jumps one to the left
• ...
• check without AND with SpellCheck!

Note (IE11):

• In IE11, adding whitespace via button DOES get surrounded with INS (= ok)! Inserting one whitespace via typing also works and gets an INS.