Implemented CMS storage for user and nodes.

Implemented role and permission storage.
Introduced the CMS_PARTIAL_NODE and CMS_PARTIAL_USER.
Added support for node storage extension
  - storage of data specific to each node content type,
  - in addition to the core CMS_NODE)
  - For now, only implemented for SQL storage.
Note: in current version, CMS_PAGE support is hard coded in the core,
    (as opposed to be only supported by the node module.)
Commented/removed for now, the Web API code to update node summary, title, via REST request.

src/service/user/cms_user_api.e

@@ -17,6 +17,12 @@ create
 
 feature -- Access
 
+	user_by_id (a_id: like {CMS_USER}.id): detachable CMS_USER
+			-- User by id `a_id', if any.
+		do
+			Result := storage.user_by_id (a_id)
+		end
+
 	user_by_name (a_username: READABLE_STRING_32): detachable CMS_USER
 			-- User by name `a_user_name', if any.
 		do
@@ -31,6 +37,65 @@ feature -- Status report
 			Result := storage.is_valid_credential (a_auth_login, a_auth_password)
 		end
 
+	user_has_permission (a_user: detachable CMS_USER; a_permission: detachable READABLE_STRING_GENERAL): BOOLEAN
+			-- Anonymous or user `a_user' has permission for `a_permission'?
+			--| `a_permission' could be for instance "create page".
+		do
+			if a_permission = Void then
+				Result := True
+			elseif a_user = Void then
+				Result := user_role_has_permission (anonymous_user_role, a_permission)
+			else
+				Result := user_role_has_permission (authenticated_user_role, a_permission)
+				if not Result then
+					Result := across user_roles (a_user) as ic some user_role_has_permission (ic.item, a_permission) end
+				end
+			end
+		end
+
+	user_roles (a_user: CMS_USER): LIST [CMS_USER_ROLE]
+		local
+			l_roles: detachable LIST [CMS_USER_ROLE]
+		do
+			l_roles := a_user.roles
+			if l_roles = Void then
+					-- Fill user with its roles.
+				create {ARRAYED_LIST [CMS_USER_ROLE]} l_roles.make (0)
+				l_roles := storage.user_roles_for (a_user)
+			end
+			Result := l_roles
+		end
+
+feature -- User roles.		
+
+	anonymous_user_role: CMS_USER_ROLE
+		do
+			if attached user_role_by_id (1) as l_anonymous then
+				Result := l_anonymous
+			else
+				create Result.make ("anonymous")
+			end
+		end
+
+	authenticated_user_role: CMS_USER_ROLE
+		do
+			if attached user_role_by_id (2) as l_authenticated then
+				Result := l_authenticated
+			else
+				create Result.make ("authenticated")
+			end
+		end
+
+	user_role_has_permission (a_role: CMS_USER_ROLE; a_permission: READABLE_STRING_GENERAL): BOOLEAN
+		do
+			Result := a_role.has_permission (a_permission)
+		end
+
+	user_role_by_id (a_id: like {CMS_USER_ROLE}.id): detachable CMS_USER_ROLE
+		do
+			Result := storage.user_role_by_id (a_id)
+		end
+
 feature -- Change User
 
 	new_user (a_user: CMS_USER)