Update bundled Cesium to 1.4
API doc updates
Don't use boolval() as that only exists in PHP 5.5 and newer
Rollback the incomplete PDF rest adapter implementation. I have come to the decision that such support is better left for external developers to implement as mapguide-rest provides sufficient hooks to add thirdparty REST adapters.
Use a new response format for JSON representations of schemas and class definitions. This format is infinitely more usable than the (converted from XML schema) form of JSON. Fixes #90