tidy: use tidy_repair_string instead of tidy_parse_string+tidy_clean_repair

A change released in tidy 5.6.0 breaks php-tidy when using
tidy_parse_string+tidy_clean_repair and wrap=0, incorrectly wrapping
every single word. Also it seems that $tidy->value should not be used to
retrieve the repaired html as far as it is undocumented and for internal
use.

We replace the call with tidy_repair_string which directly returns the
repaired string.

Relates to https://github.com/htacg/tidy-html5/issues/673
Relates to https://bugs.php.net/bug.php?id=75947

Tests pass.

Signed-off-by: Kevin Decherf <kevin@kdecherf.com>

src/Readability.php

@@ -274,10 +274,10 @@ class Readability implements LoggerAwareInterface
         if ($this->useTidy) {
             $this->logger->debug('Tidying document');
 
-            $tidy = tidy_parse_string($this->html, $this->tidy_config, 'UTF8');
-            if (tidy_clean_repair($tidy)) {
+            $tidy = tidy_repair_string($this->html, $this->tidy_config, 'UTF8');
+            if (false !== $tidy && $this->html !== $tidy) {
                 $this->tidied = true;
-                $this->html = $tidy->value;
+                $this->html = $tidy;
                 $this->html = preg_replace('/[\r\n]+/is', "\n", $this->html);
             }
             unset($tidy);