Compare performance improvements through caching

Some more aggressive performance improvements for the compare algorithm through caching the getAllSchemas() result.

* The result for Schema.getAllSchemas() and Types.getAllSchemas() is cached
* Looking up a TypeDefinition in a Schema tree is cached 

For our WSDLs who pull in a lot of Schemas this results in a 90% speedup. Our longest running WSDL comparison went from taking 90 seconds to taking 8 seconds after these improvements.