[form] fix #719285, due to multiple calls to restore_previous_post, by proper refactorings * move __init__ code from FieldsForm to Form. Must behaviour here should actually be in the Form base class * avoid buggy duplicated call to restore_previous_post * move some code that was in the form renderer to the form'__init__ method (__redirectpath & __form_id hidden input handling)) * 'formvid' should now be specified on form selection, not on form rendering

Add some entities
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As manager, you can access to entity creation forms by using the `site management`_ page.

.. _`site management`: manage

As regular user, the index page or the action box may propose some links to create entities according to the context.