Improved taxonomy by supporting tags, multiple terms allowed, and required kind of vocabulary for specific content type.

Updated node web form, to support taxonomy editing if allowed (specific support for CMS_VOCABULARY.is_tags: BOOLEAN).
Added notion of required or optional module dependencies.

modules/node/cms_node_module.e

@@ -41,6 +41,9 @@ feature {NONE} -- Initialization
 			description := "Service to manage content based on 'node'"
 			package := "core"
 			config := a_setup
+				-- Optional dependencies, mainly for information.
+			put_dependency ({CMS_RECENT_CHANGES_MODULE}, False)
+			put_dependency ({CMS_TAXONOMY_MODULE}, False)
 		end
 
 	config: CMS_SETUP