rename 'Stylepicker4ward' to 'MetaModelsPicker' see #318

There is a language var missing? -> `$GLOBALS['TL_LANG']['MSC']['metamodelspicker_noItems']` and `$GLOBALS['TL_LANG']['MSC']['metamodelspicker']`

Which text schould be placed in there?
Yes, it was not there...
ANy reference where I can look on?