[3.1.0] Implement a few phpt, fix some autoload bugs

- Make our autoload handler polite, ensuring that any __autoload() 
functions get added
- Modify phpt calling code so that each phpt files gets its own 
test-case (this lets us run one phpt file at a time)
- Implement phpt for loading, which test varying loading methods of HTML 
Purifier
- Add --disable-phpt and --only-phpt flags
- More descriptive veto messages, also fix test count



git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1552 48356398-32a2-884e-a903-53898d9a118a

tests/HTMLPurifier/PHPT/loading/auto-with-autoload.phpt

@@ -0,0 +1,25 @@
+--TEST--
+HTMLPurifier.auto.php using spl_autoload_register with __autoload() already defined loading test
+--SKIPIF--
+<?php
+if (!function_exists('spl_autoload_register')) {
+    echo "skip spl_autoload_register() not available";
+}
+--FILE--
+<?php
+function __autoload($class) {
+    echo "Autoloading $class..." . PHP_EOL;
+    eval("class $class {}");
+}
+
+require_once '../library/HTMLPurifier.auto.php';
+$config = HTMLPurifier_Config::createDefault();
+$purifier = new HTMLPurifier($config);
+echo $purifier->purify('<b>Salsa!') . PHP_EOL;
+
+// purposely invoke older autoload
+$bar = new Bar();
+
+--EXPECT--
+<b>Salsa!</b>
+Autoloading Bar...