objects[] infrastructure

The bases[] array allows finding the index of the first object in
a particular class.  Extend it so that bases[class + 1] - 1 is a
reliable way to find the last object in any class.  The array had
to be extended by one so that the last class has a [class+1] entry
available, and object initialization now makes sure that classes
within objects[] are in ascending order so that [class+1] always
holds a higher index than [class].

include/decl.h

@@ -713,7 +713,7 @@ struct instance_globals {
     const char *hname; /* name of the game (argv[0] of main) */
     int hackpid; /* current process id */
     char chosen_windowtype[WINTYPELEN];
-    int bases[MAXOCLASSES];
+    int bases[MAXOCLASSES + 1];
     int multi;
     const char *multi_reason;
     int nroom;