Extracted page support from cms_node_module, and add a proper CMS_PAGE_MODULE.

- now, the CMS_PAGE_MODULE has to be declared in the related CMS_SETUP via CMS_EXECUTION.
   (See demo for example)

Improved the export facilities.
  Implemented blog and page export.
Added import facilities.
  Implemented blog and page import.

Improved node revision web interface (allow to edit a past revision, in order to restore it as latest revisionm i.e current).
Removed specific tag from blog module, and reuse the taxonomy module for that purpose.

Added WIKITEXT module that provide a WIKITEXT_FILTER, so now we can have wikitext content.
   - for now, no support for wiki links such as [[Foobar]].

modules/node/handler/node_form_response.e

@@ -30,7 +30,15 @@ feature -- Execution
 						location.ends_with_general ("/edit") and then
 						node_api.has_permission_for_action_on_node ("edit", l_node, user)
 					then
-						edit_node (l_node, l_type, b)
+						if
+							attached {WSF_STRING} request.query_parameter ("revision") as p_rev and then
+							p_rev.value.is_integer_64 and then
+							attached node_api.revision_node (l_node.id, p_rev.value.to_integer_64) as l_rev_node
+						then
+							edit_node (l_rev_node, l_type, l_rev_node.revision < l_node.revision, b)
+						else
+							edit_node (l_node, l_type, False, b)
+						end
 					elseif
 						location.ends_with_general ("/delete") and then
 						node_api.has_permission_for_action_on_node ("delete", l_node, user)
@@ -118,12 +126,15 @@ feature {NONE} -- Create a new node
 		end
 
 
-	edit_node (a_node: CMS_NODE; a_type: CMS_NODE_TYPE [CMS_NODE]; b: STRING_8)
+	edit_node (a_node: CMS_NODE; a_type: CMS_NODE_TYPE [CMS_NODE]; is_old_revision: BOOLEAN; b: STRING_8)
 		local
 			f: like new_edit_form
 			fd: detachable WSF_FORM_DATA
 		do
 			f := new_edit_form (A_node, url (location, Void), "edit-" + a_type.name, a_type)
+			if is_old_revision then
+				add_warning_message ("You are editing old revision #" + a_node.revision.out + " !")
+			end
 			api.hooks.invoke_form_alter (f, fd, Current)
 			if request.is_post_request_method then
 				f.validation_actions.extend (agent edit_form_validate (?, b))
@@ -135,6 +146,7 @@ feature {NONE} -- Create a new node
 				add_to_menu (node_local_link (a_node, translation ("View", Void)), primary_tabs)
 				add_to_menu (create {CMS_LOCAL_LINK}.make (translation ("Edit", Void), node_api.node_path (a_node) + "/edit"), primary_tabs)
 				add_to_menu (create {CMS_LOCAL_LINK}.make ("Delete", node_api.node_path (a_node) + "/delete"), primary_tabs)
+				add_to_menu (create {CMS_LOCAL_LINK}.make ("Revisions", node_api.node_path (a_node) + "/revision"), primary_tabs)
 			end
 
 			if attached redirection as l_location then