Do not deactivate-mark if region active
Prefer advice over remap exchange-point-and-mark
Merge pull request #570 from toctan/exchange-point-and-mark

Do not deactivate-mark if region active when exchange-point-and-mark
Merge remote-tracking branch 'bbatsov/master'

* bbatsov/master:
  Prefer advice over remap exchange-point-and-mark
  Do not deactivate-mark if region active