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]].

src/hooks/export/cms_hook_export.e

@@ -13,19 +13,19 @@ inherit
 
 feature -- Hook	
 
-	export_to (a_export_id_list: detachable ITERABLE [READABLE_STRING_GENERAL]; a_export_parameters: CMS_EXPORT_PARAMETERS; a_response: CMS_RESPONSE)
+	export_to (a_export_id_list: detachable ITERABLE [READABLE_STRING_GENERAL]; a_export_ctx: CMS_EXPORT_CONTEXT; a_response: CMS_RESPONSE)
 			-- Export data identified by `a_export_id_list',
 			-- or export all data if `a_export_id_list' is Void.
 		deferred
 		end
 
---	export_identifiers: detachable ITERABLE [READABLE_STRING_32]
+--	export_identifiers: detachable ITERABLE [READABLE_STRING_GENERAL]
 --			-- Optional list of exportation ids, if any.
 --		do
 --				-- To redefine if needed.
 --		end
 
 note
-	copyright: "2011-2015, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
+	copyright: "2011-2017, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
 	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
 end