R919 - applying lances

Fixes 2 bugs:
1) an impossible() could occur if you applied a lance against a long worm
because the code uses thitmonst to do the hitting, but didn't set bhitpos,
which is required before calling thitmonst.
Add the missing assignment.
2) applying a lance would never mark a knight as a caitiff.  Added a new
check_caitiff function and called it from the 2 existing checks and in
the lance code.

src/dokick.c

@@ -61,14 +61,7 @@ register boolean clumsy;
 
 	if(mon->m_ap_type) seemimic(mon);
 
-	/* it is unchivalrous to attack the defenseless or from behind */
-	if (Role_if(PM_KNIGHT) &&
-		u.ualign.type == A_LAWFUL && u.ualign.record > -10 &&
-		(!mon->mcanmove || mon->msleeping ||
-		(mon->mflee && !mon->mavenge))) {
-	    You_feel("like a caitiff!");
-	    adjalign(-1);
-	}
+	check_caitiff(mon);
 
 	/* squeeze some guilt feelings... */
 	if(mon->mtame) {