[views/templates] provide a modal main template (closes #3274672) The current NonTemplatableViewTemplate may seem to provide the desired feature if a '__notemplate' is provided in the form, unfortunately, it: * wraps the view in a spurious div * calls view.set_stream(), which has the effect of wiping any js/css resource recorded until then by the view, leading to hard-to-track missing resources symptoms

change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')