Significant improvement on "Replace one-by-one" and "Detailed hits"

• The "Detailed hits" report now removes everything from the Preview pane that was removed from the
  hit list by the user, be it with the <DEL> key or via the context menu.
• The "Replace one-by-one" dialog now has a "Fix this and all remaining objects" button.
• The "Replace-one-by-one" dialog now starts with check boxes unticked. It therefore initially shows
  what has been searched for rather than the result after the replace.
• The TreeView on the "Replace-one-by-one" dialog now supports Ctrl+A (for ticking all check boxes) and
  Ctrl+N (for un-ticking all check boxes).
• The "Replace-one-by-one" list has now a context menu ("Select all" & "Deselect all")
• Bug fixes:
  • The "Replace one-by-one" dialog moved down by the height of the menubar with every object.
  • The report in the statusbar of the "Replace one-by-one" was sometimes mutilated.
  • The "Skip" button in the "Replace one-by-one" dialog was active even when there were no more objects
    waiting.
  • The cause for the spurious "xyz cannot own abc" message in the status window has been removed.
  • Some acre-related test were not executed any more because they concluded (wrongly) that the version of acre to be found in ⎕SE was outdated when in fact it was "too good".
• Internally: new test framework Tester2 is now used.