fix #H2785 - engraving punctuation

Message tidbit when engraving with a weapon which becomes too dull to
finish the whole text:  add missing final period to
  You are only able to write "<partial text>".
I think that proper usage puts the period in front of the quote rather than
after, but that could make it look as if the period ended up inside the
partial engraving.

doc/fixes35.0

@@ -845,6 +845,8 @@ very fast hero would sometimes take two consecutive moves with very fast
 when a monster zapped by polymorph drops inventory because of its new form,
 	don't let that same zap hit the dropped item(s)
 entering an untended shop while blind gave an inappropriate message
+engraving feedback about partial text when weapon became too dull to finish
+	was lacking sentence-ending period
 
 
 Platform- and/or Interface-Specific Fixes

src/engrave.c

@@ -1115,7 +1115,7 @@ doengrave()
 	    if (!maxelen && *sp) {
 		*sp = (char)0;
 		if (multi) nomovemsg = "You cannot write any more.";
-		You("only are able to write \"%s\"", ebuf);
+		You("only are able to write \"%s\".", ebuf);
 	    }
 	}