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/auth/cms_authentication_module.e

@@ -599,7 +599,7 @@ feature -- Handler
 					end
 				elseif attached {WSF_STRING} req.form_parameter ("username") as l_username then
 					if
-						attached {CMS_USER} l_user_api.user_by_name (l_username) as l_user and then
+						attached {CMS_USER} l_user_api.user_by_name (l_username.value) as l_user and then
 						attached l_user.email as l_user_email
 					then
 							-- User exist create a new token and send a new email.