Verbatim-safe typography, ^-punctuation quoting, full-range ^UUUU^, polyglot html

Typographic transforms (---, quote pairs, ~) no longer touch verbatim
text: @c/@code/@source_listing content and ^'...'^ spans show exactly the
characters written. "^" before any punctuation character quotes it in
every target (the apostrophe excepted: ^' opens a literal span), with the
new :resolve option on @@@target declaring per-target renderings. The
^UUUU^ code-point form accepts 4-6 hex digits, the full Unicode range.
The html output and transform spellings are polyglot (XML-valid), in
preparation for an EPUB target. New suites: transform_test, character_test
(engine), typography_test (SKS).

(from dev 07ce5ea86a0a)

sks/kutil/kutil.py

@@ -21,10 +21,11 @@ def msg(text=""):
 
 def escape(s):
     result = s
-
+    # These were commented out -- has it been replaced?
+    # It's only used in kutil/klammer_base.py and block/block.py
+    # and does nothing now.
     #result = re.sub(r"\b", r"\b", result)
     #result = re.sub(r"\t", r"\t", result)
-
     #result = re.sub("\f", r"\\f", result)
     #result = re.sub("\v", r"\\v", result)
     #result = re.compile("\\(.)").sub(r"\\\1", result)