Unify /values and /pathpage with changed layout

* Only /values and /values.data remains
* It now shows URIs, literals, and blank nodes with complete descriptions
* Values pages now look more similar to normal resource pages
* Removed SPARQL endpoint link from footer -- it's often undesirable
* Removed links to RDF browsers from the footer -- they were all broken
Refactored to introduce DataSource and IRIRewriter

* Major refactoring and cleanup
* Expressed much of the logic in terms of new DataSource and IRIRewriter interfaces
* Fixed many bugs around inconsistent rewriting of URIs in the process
* Started to change terminology from "URI" to "IRI", not yet done
* Re-did much of the configuration parsing/reading
* Improved detection and display of problems in configuration file
* Moved metadata stuff into its own class (MetadataConfiguration)
* Metadata templates are now expected in /WEB-INF rather than /WEB-INF/templates
* Removed obscure feature: conf:fixUnescapedCharacters