[PATCH] Gracefully handle titles of numberless chapters

[Ludovic Courtès]

Hi,

Currently, when using the `book' style and producing a numberless
chapter with:

  @Chapter @Title { Some Title }
           @BypassNumber { }     # we want a numberless chapter

the chapter heading looks like this:

  Chapter.  Some Title

The attached patch fixes address@hidden' so that it gracefully
handles this case, yielding a chapter heading more consistent with what
one might expect, namely:

  Some Title

Thanks,
Ludovic.

--- orig/include/dsf
+++ mod/include/dsf
@@ -5189,7 +5189,12 @@
        def @LongNum
        {
            numbers @Then {
-               initiallanguage @Language { word @NumSep @ShortNum }
+               @ShortNum @Case {
+                  ""   @Yield { } # numberless: don't produce `word'
+                  else @Yield {
+                    initiallanguage @Language { word @NumSep @ShortNum }
+                  }
+               }
            }
        }