[core] Dropped AllowAnywhereRecoding configuration variable.

It really does not make sense these days, now the recoding of
export/import is available when the necessary extensions are loaded and
it is possible to disable it using RecodingEngine directive.

setup/lib/forms.inc.php

@@ -74,7 +74,6 @@ $forms['Server_tracking'] = array('Servers' => array(1 => array(
 $forms['Import_export'] = array(
     'UploadDir',
     'SaveDir',
-    'AllowAnywhereRecoding',
     'RecodingEngine',
     'IconvExtraParams',
     'ZipDump',