subs: Make shp_check_nav() more like lnd_check_mar()

No functional change.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/types.h

@@ -27,7 +27,7 @@
  *  types.h: Empire types
  *
  *  Known contributors to this file:
- *     Markus Armbruster, 2006-2013
+ *     Markus Armbruster, 2006-2014
  */
 
 #ifndef TYPES_H
@@ -36,14 +36,6 @@
 typedef unsigned char natid;	/* NSC_NATID must match this */
 typedef short coord;
 
-enum d_navigation {
-    NAV_NONE,	/* ships can't navigate */
-    NAVOK,	/* ships can always navigate */
-    NAV_02,	/* requires 2% effic to navigate */
-    NAV_CANAL,	/* requires 2% effic to navigate and M_CANAL capability */
-    NAV_60	/* requires 60% effic to navigate */
-};
-
 struct bp;
 struct emp_qelem;
 struct empobj;