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/font/font.py

@@ -33,7 +33,7 @@ def html_fontify(text, font_symbol, font_size):
     result = text
     if cls:
         if font_symbol == "c":
-            result = re.sub(" ", " ", result)
+            result = re.sub(" ", " ", result)
         cls = f'class="{cls}"'
     sty = ""
     if font_size != 1: