Remove error.php

Redirecting to other script introduces possibility of inject custom
messages to it. Though there is no clear security issue in this, it
might confuse users and mistake them to go to external site as it allows
to include links.

Conflicts:

	error.php
	libraries/core.lib.php

libraries/common.inc.php

@@ -325,7 +325,6 @@ $goto_whitelist = array(
     'db_printview.php',
     'db_search.php',
     //'Documentation.html',
-    //'error.php',
     'export.php',
     'import.php',
     //'index.php',