Refactored and update CMS hooks design. (Move from CMS_RESPONSE to CMS_API).

Moved content_types and content_type_webform_managers from CMS_RESPONSE to CMS_API.
Updated the way to output content (node, ...) to html page.
   See CMS_CONTENT_TYPE_WEBFORM_MANAGER.append_cointent_as_html_to (...).
   Added notion of "teaser" (short version of the content), as opposed to full content.
One can use CMS_API.html_encoder ... when possible, same for `formats', ...
Added bridge from CMS_MODULE_API to CMS_API's encoders.
Added new CMS_TAXONOMY_HOOK used to retrieve list of content associated with a specific term.
Moved up to CMS_RESPONSE a few features which was available only in specific descendants.

Added /taxonomy/term/{termid} implementation.

modules/admin/handler/user/cms_user_form_response.e

@@ -86,7 +86,7 @@ feature -- Process Edit
 		do
 			create b.make_empty
 			f := new_edit_form (a_user, url (location, Void), "edit-user")
-			hooks.invoke_form_alter (f, fd, Current)
+			api.hooks.invoke_form_alter (f, fd, Current)
 			if request.is_post_request_method then
 				f.submit_actions.extend (agent edit_form_submit (?, a_user, b))
 				f.process (Current)
@@ -118,7 +118,7 @@ feature -- Process Delete
 		do
 			create b.make_empty
 			f := new_delete_form (a_user, url (location, Void), "edit-user")
-			hooks.invoke_form_alter (f, fd, Current)
+			api.hooks.invoke_form_alter (f, fd, Current)
 			if request.is_post_request_method then
 				f.process (Current)
 				fd := f.last_data
@@ -151,7 +151,7 @@ feature -- Process New
 		do
 			create b.make_empty
 			f := new_edit_form (l_user, url (location, Void), "create-user")
-			hooks.invoke_form_alter (f, fd, Current)
+			api.hooks.invoke_form_alter (f, fd, Current)
 			if request.is_post_request_method then
 				f.validation_actions.extend (agent new_form_validate (?, b))
 				f.submit_actions.extend (agent edit_form_submit (?, l_user, b))