Add Text_Highlighter to Composer

- Fixes critical mistake in boot.php regarding set_include_path
- Fixes minor mistake in text.php regarding strpos order of arguments

Note: This change significantly increases Composer running time because
Text_Highlither is a PEAR package. I'm already planning to replace it
with scrivo/highlight.php.

vendor/composer/autoload_real.php

@@ -23,6 +23,10 @@ class ComposerAutoloaderInitFriendica
         self::$loader = $loader = new \Composer\Autoload\ClassLoader();
         spl_autoload_unregister(array('ComposerAutoloaderInitFriendica', 'loadClassLoader'));
 
+        $includePaths = require __DIR__ . '/include_paths.php';
+        array_push($includePaths, get_include_path());
+        set_include_path(implode(PATH_SEPARATOR, $includePaths));
+
         $useStaticLoader = PHP_VERSION_ID >= 50600 && !defined('HHVM_VERSION') && (!function_exists('zend_loader_file_encoded') || !zend_loader_file_encoded());
         if ($useStaticLoader) {
             require_once __DIR__ . '/autoload_static.php';