Refactored and update CMS hooks design. (Move from CMS_RESPONSE to CMS_API).

Moved content_types and content_type_webform_managers from CMS_RESPONSE to CMS_API.
Updated the way to output content (node, ...) to html page.
   See CMS_CONTENT_TYPE_WEBFORM_MANAGER.append_cointent_as_html_to (...).
   Added notion of "teaser" (short version of the content), as opposed to full content.
One can use CMS_API.html_encoder ... when possible, same for `formats', ...
Added bridge from CMS_MODULE_API to CMS_API's encoders.
Added new CMS_TAXONOMY_HOOK used to retrieve list of content associated with a specific term.
Moved up to CMS_RESPONSE a few features which was available only in specific descendants.

Added /taxonomy/term/{termid} implementation.

modules/taxonomy/handler/cms_taxonomy_entity.e

@@ -0,0 +1,44 @@
+note
+	description: "[
+			Information related to content or taxonomy entity in a taxonomy container.
+			
+			Mainly used to build list of contents/entities associated with a term.
+		]"
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	CMS_TAXONOMY_ENTITY
+
+inherit
+	COMPARABLE
+
+create
+	make
+
+feature {NONE} -- Initialization
+
+	make (a_content: CMS_CONTENT; a_date: DATE_TIME)
+			-- Build Current information from `a_content' dated by `a_date'.
+		do
+			content := a_content
+			date := a_date
+		end
+
+feature -- Access
+
+	content: CMS_CONTENT
+			-- Content of the entity.
+
+	date: DATE_TIME
+			-- Date, usually related to last modification.
+
+feature -- Comparison
+
+	is_less alias "<" (other: like Current): BOOLEAN
+			-- Is current object less than `other'?
+		do
+			Result := date < other.date
+		end
+
+end