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/eval_cpp.cpp

@@ -34,7 +34,7 @@ std::string Eval_cpp::eval(const fs::path& library_path, const std::string& func
         std::stringstream ss {};
         ss << "Cannot load symbol " << function_name
            << " from library " << library_path << ":\n  " << error_desc;
-        throw File_error(ss.str(), m_loc, false);
+        throw File_error(ss.str(), m_loc);
     }
     std::string result = func(m_machine);
     dlclose(handle);