\#dotypeinv ('I') - show title for inventory subset

When asking for an inventory subset for one of the meta-classes that
can generate output which spans object classes (so B,U,C,X, and P),
insert a title at the start of the resulting inventory list.  (Iu and
Ix produce alternate output that already includes a title.)

Also, stop handling '$' differently for menustyles traditional and
combination from full and partial.  'I$' was running the '$' command
for the first two styles but just showing the inventory entry for
gold for the last two.  Change to the latter for all styles.

include/decl.h

@@ -957,6 +957,7 @@ struct instance_globals {
     winid cached_pickinv_win;
     /* query objlist callback: return TRUE if obj type matches "this_type" */
     int this_type;
+    const char *this_title; /* title for inventory list of specific type */
     /* query objlist callback: return TRUE if obj is at given location */
     coord only;