mon_pmname(), obj_pmname()

Revive some code from 5 or so years ago that's been sitting in a
defunct local git branch.  There are a couple of references to
figurines having gender; the old, unfinished code did already have
support for that, the current code doesn't.  It probably won't take
much effort to add it in but I want to get this first part out of
the way.

Replace some of the
pmname(mon->data, Mgender[mon]) calls with simpler
mon_pmname(mon) and some
pmname(&mons[statue->corpsenm],
   (statue->spe & CORPSTAT_GENDER) == ... ? ... : ...) with simpler
obj_pmname(obj).  There are other instances of them which haven't
been changed but could be.

include/extern.h

@@ -451,6 +451,8 @@ extern const char *lookup_novel(const char *, int *);
 extern int Mgender(struct monst *);
 extern const char *pmname(struct permonst *, int);
 #endif
+extern const char *mon_pmname(struct monst *);
+extern const char *obj_pmname(struct obj *);
 
 /* ### do_wear.c ### */