Scribble soft-hyphen support for Latex rendering; ?-' in scribble/base'

original commit: 21d324a1696daa84954959696052163fa5488021

collects/scribble/base.rkt

@@ -262,11 +262,12 @@
 
 ;; ----------------------------------------
 
-(provide ._ .__ ~ -~-)
+(provide ._ .__ ~ ?- -~-)
 
 (define ._ (make-element (make-style "Sendabbrev" null) "."))
 (define .__ (make-element (make-style "Sendsentence" null) "."))
 (define ~ "\uA0")
+(define ?- "\uAD")
 (define -~- "\u2011")
 
 ;; ----------------------------------------

collects/scribble/latex-render.rkt

@@ -626,6 +626,7 @@
                                     c)]
                      [(#\# #\% #\& #\$) (format "\\~a" c)]
                      [(#\uA0) "~"] ; non-breaking space
+                     [(#\uAD) "\\-"] ; soft hyphen; unfortunately, also disables auto-hyphen
                      [(#\uDF) "{\\ss}"]
                      [else
                       (if ((char->integer c) . > . 127)

collects/scribblings/scribble/base.scrbl

@@ -367,6 +367,12 @@ which is equivalent to @racket['nbsp] as an element.}
 A string containing the non-breaking hyphen character.}
 
 
+@defthing[?- string?]{
+
+A string containing the soft-hyphen character (i.e., a suggestion of
+where to hyphenate a word to break it across lines when rendering).}
+
+
 @defthing[._ element?]{
 
 Generates a period that ends an abbreviation in the middle of a