If a tab is rendered inline make a simple check and show a message to user if tab can not be rendered.
This is especially nasty when for example user tries to open a tab, it fails (then tabs' Id cookie is saved in user browser). Next page view will brake whole ERP5 front page (then this failing tab is loaded inlined).

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32783 20353a03-c40f-0410-a6d1-a30d3c3de9de