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)

mac/error.cpp

@@ -23,8 +23,7 @@ void Error::print_message(const std::string& epilog)
     if (epilog != "") {
         m_desc += "\n\n" + epilog + "\n";
     }
-    if (m_just)
-        m_desc = justify(m_desc, 80, 0);
+    m_desc = justify(m_desc, 80, 0);
     std::cerr << "\n" << red << command_name << " (" << m_type << " error)";
     if (display_source(m_loc.m_filename)) {
         std::cerr << ":\n  " << m_loc.m_filename;