Follow-up to engraving punctuation

Skip the terminal period only if there is true punctuation at the end of
the engraving, not degraded text.  This feels a bit janky because the
way engravings are malloced and structured uses this manual offset to
access the space allocated for text.  I used a macro to unify all those
accesses so that it will be harder to screw it up if something changes
in that respect, since repeating (ep + 1) as a magic number across
engrave.c seems quite brittle.

include/engrave.h

@@ -13,6 +13,8 @@ enum engraving_texts {
     text_states
 };
 
+#define engr_text_space(ep) ((char *) ((ep) + 1))
+
 struct engr {
     struct engr *nxt_engr;
     char *engr_txt[text_states];