Change SAVE-EXCURSION and SCREEN-WINDOW-CONFIGURATION to make

Change SAVE-EXCURSION and SCREEN-WINDOW-CONFIGURATION to make
right-inserting copies of the point, rather than left-inserting.
This way, insertion of text at point inside the SAVE-EXCURSION region
will have no effect on the original point.

Change SAVE-EXCURSION to select the original buffer after the
supplied thunk returns.

Remove PAREDIT-SAVE-EXCURSION, whose functionality is now subsumed by
the new SAVE-EXCURSION.