\#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.

src/decl.c

@@ -432,8 +432,9 @@ const struct instance_globals g_init = {
     NULL, /* invbuf */
     0, /* inbufsize */
     WIN_ERR, /* cached_pickinv_win */
-    UNDEFINED_VALUE,
-    UNDEFINED_VALUES,
+    0, /* this_type */
+    NULL, /* this_title */
+    UNDEFINED_VALUES, /* only (coord) */
 
     /* light.c */
     NULL, /* light_source */