obj->oextra->{omid,olong}

Change obj->oextra->omid from a usually-Null pointer field in
oextra to a simple 'unsigned' that doesn't need any allocation
beyond obj->oextra itself.  Value 0 means that it is not in use;
it is used to hold a monst.m_id and those are always non-zero.

Delete unused obj->oextra->olong.  'olong' used to be the last
field in struct obj, put there to force alignment of anything
which followed it back when obj structures were over-allocated to
append extra information.  It had a comment about being used for
temporary gold but whatever that was, temporary gold was gone long
before obj->oextra got introduced.

Bump EDITLEVEL since this invalidates existing 3.7 save files.

Remove a bunch of tabs from obj.h and save.c.

src/cmd.c

@@ -2295,12 +2295,9 @@ struct obj *otmp;
             sz += (int) strlen(ONAME(otmp)) + 1;
         if (OMONST(otmp))
             sz += size_monst(OMONST(otmp), FALSE);
-        if (OMID(otmp))
-            sz += (int) sizeof (unsigned);
-        if (OLONG(otmp))
-            sz += (int) sizeof (long);
         if (OMAILCMD(otmp))
             sz += (int) strlen(OMAILCMD(otmp)) + 1;
+        /* sz += (int) sizeof (unsigned); -- now part of oextra itself */
     }
     return sz;
 }