(pln_oneway_to_carrier_ok): New.

(fly, reco): Use it to prevent flying to a carrier that doesn't have
space for the planes.  Previously, planes that did this were
teleported home, which could be abused.

(fly): Fail if pln_sel() comes up empty, just like the other commands
to fly planes.

src/lib/commands/reco.c

@@ -115,6 +115,10 @@ reco(void)
     wantflags |= P_ESC;
     pln_sel(&ni_esc, &esc_list, &ap_sect, ap_to_target,
 	    1, wantflags, P_M | P_O);
+    if (cno >= 0 && !pln_oneway_to_carrier_ok(&bomb_list, &esc_list, cno)) {
+	pr("Not enough room on ship #%d!\n", cno);
+	return RET_FAIL;
+    }
     /*
      * now arm and equip the bombers, transports, whatever.
      */