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)

tst/alone_test.sh

@@ -87,7 +87,7 @@ check_error() {
         FAIL=$((FAIL + 1))
         return
     fi
-    if echo "$output" | grep -qF "$pattern"; then
+    if echo "$output" | tr '\n' ' ' | tr -s ' ' | grep -qF "$pattern"; then
         echo "${green}PASS${reset} $test_name"
         PASS=$((PASS + 1))
     else
@@ -233,6 +233,14 @@ check_eq \
     "[]" \
     --klammersets none -s '@@s :t.word : [*t*] @@ @s :t @' -d
 
+echo
+# --- The pattern itself is validated at definition time (gallery review) ---
+
+check_error \
+    "22. an invalid :pattern is a definition-time error" \
+    "is not a valid regular expression" \
+    --klammersets none -s '@@@argtype bad | d :pattern ([ @@@' -d
+
 echo
 echo "================================"
 echo "Passed: $PASS  Failed: $FAIL"