Removed unused implementations of SiteMapNode.
Removed url resolver and visibility provider injection from XmlSiteMapBuilder and ReflectionSiteMapBuilder because they are not refereced.
Added provider strategy implementations for SiteMapNodeUrlResolver and SiteMapNodeVisibilityProvider.
Added SiteMapLoader to manage creation and caching of sitemaps. Added SiteMaps class with static members as a starting point.  Migrated the Web namespace and converted to use SiteMaps and the SiteMap datatypes.
Made adjustments to cache, SiteMap, and SiteMapNode so they will be compatible with the UI components.
Made adjustments to cache, SiteMap, and SiteMapNode so they will be compatible with the UI components.
Fixed StructureMap configuration so the new objects are composed without exceptions.