(ediff-mark-for-hiding-at-pos)

(ediff-mark-for-hiding-at-pos)
(ediff-mark-for-operation-at-pos): Renamed from
ediff-mark-for-hiding, ediff-mark-for-operation.
(ediff-mark-session-for-hiding, ediff-mark-session-for-operation)
(ediff-unmark-all-for-operation, ediff-unmark-all-for-hiding): New
functions.
(ediff-setup-meta-map): Changed bindings.