Add flags to refresh-client (-U -D -L -R and -c) to pan a window that

is larger than the client manually. Bound to S-Up, S-Down, S-Left,
S-Right and Delete manually.

Also add aliases for keys DC = Delete, IC = Insert, and make
refresh-client -C accept XxY as well as X,Y to match default-size.

key-string.c

@@ -43,7 +43,9 @@ static const struct {
 	{ "F11",	KEYC_F11 },
 	{ "F12",	KEYC_F12 },
 	{ "IC",		KEYC_IC },
+	{ "Insert",     KEYC_IC },
 	{ "DC",		KEYC_DC },
+	{ "Delete",     KEYC_DC },
 	{ "Home",	KEYC_HOME },
 	{ "End",	KEYC_END },
 	{ "NPage",	KEYC_NPAGE },