Templating v2

* Business rules; added dynamic configurable business rules to be used
for various needs, for example selecting the template for a requested
URL.
* Template; added a "template" custom post type, which holds references
to sitewide elements (header, subheader, sidebar, etc.etc).
* TemplatePart; added a "templatepart" custom post type, which can be
used to template content of posts and pages, as well as archives (lists)
* Header now uses header_post_id referenced by template (derived from
business rules)
* Added business rule widgets for "catch all" and "postid" (to be
extended)
* Added templateprops widget for storing site wide elements of
"Template"s
* Blog entry now uses business rule engine to derived templateproperties
(so far only header_postid is overriden)
* Pageslider still "choked" when "undefined" element was stored in it