new makemon() flag

add a flag to makemon() to allow monster to be created adjacent to the supplied  coordinates if there is already a monster at the target location

include/hack.h

@@ -140,6 +140,7 @@ NEARDATA extern coord bhitpos;	/* place where throw or zap hits or stops */
 #define MM_NONAME	  0x20  /* monster is not christened */
 #define MM_NOCOUNTBIRTH	  0x40  /* don't increment born counter (for revival) */
 #define MM_IGNOREWATER	  0x80	/* ignore water when positioning */
+#define MM_ADJACENTOK	  0x100 /* its acceptable to use adjacent coordinates */
 
 /* flags for special ggetobj status returns */
 #define ALL_FINISHED	  0x01  /* called routine already finished the job */