REFACTOR: top____ are now centrally calculated, e.mozInnerScreen_ is now stored in this.MouseScreenPos, future changes need to know the 'last mouse position'
ADDED: To ant build a target which would strip <debug> ... </debug> lines from the build before packaging.  Currently commented out as decided not to use it.
REFACTOR: Refactored creation of a highlight rect element into its own SnapLinksDebug.CreateHighlightRect() function, ShowClientElementRects() now calls that.
BUGFIX: Out of viewport selection of links in a 1st-level sub-frame was not working properly, links were being filtered out.
ADDED: Debug code to show overlays of various calculation rects. (commented out for future use).
CLEANUP: Cleaned up the test_links.htm of PhpStorm warnings.
CHANGE: MouseCoordinates box for test page to be out of the way unless needed.