Implemented view node by content type (no more hardcoded cases).

Added CMS_NODE_TYPE as descendant of CMS_CONTENT_TYPE,
  in case we have content which is not a node in the future.
  (probably useless, but for now, this extra abstraction is harmful)
Moved all node related code under node module cluster.
Applied comments from Javier Velilla.
Code cleaning.

src/service/cms_module_collection.e

@@ -0,0 +1,81 @@
+note
+	description: "Summary description for {CMS_MODULE_COLLECTION}."
+	author: ""
+	date: "$Date: 2015-02-09 22:29:56 +0100 (lun., 09 févr. 2015) $"
+	revision: "$Revision: 96596 $"
+
+class
+	CMS_MODULE_COLLECTION
+
+inherit
+	ITERABLE [CMS_MODULE]
+
+create
+	make
+
+feature {NONE} -- Initialization
+
+	make (nb: INTEGER)
+		do
+			create modules.make (nb)
+		end
+
+feature -- Access
+
+	new_cursor: INDEXABLE_ITERATION_CURSOR [CMS_MODULE]
+			-- <Precursor>
+		do
+			Result := modules.new_cursor
+		end
+
+feature -- Status report
+
+	has (a_module: CMS_MODULE): BOOLEAN
+			-- Has `a_module'?
+		do
+			Result := modules.has (a_module)
+		end
+
+	has_module_with_same_type (a_module: CMS_MODULE): BOOLEAN
+			-- Has module of type `a_type' already inserted?
+		local
+			l_type: TYPE [detachable CMS_MODULE]
+		do
+			l_type := a_module.generating_type
+			across
+				modules as ic
+			until
+				Result
+			loop
+				Result := ic.item = a_module or else ic.item.generating_type = l_type
+			end
+		end
+
+	count: INTEGER
+			-- Number of modules.
+		do
+			Result := modules.count
+		end
+
+feature -- Element change
+
+	extend (a_module: CMS_MODULE)
+			-- Add module
+		do
+			if not has (a_module) then
+				modules.force (a_module)
+			end
+		end
+
+	remove (a_module: CMS_MODULE)
+			-- Remove module
+		do
+			modules.prune_all (a_module)
+		end
+
+feature {NONE} -- Implementation		
+
+	modules: ARRAYED_LIST [CMS_MODULE]
+			-- List of available modules.
+
+end