- Fixed HTML doc formatting in pdp.xsd and improved content.

- Upgraded authzforce-ce-core-pdp-api version to 16.1.0 adding
PolicyProvider#getCandidateRootPolicy() interface
- Changed PDP config XSD
	- Simplified versioning (version="7.1" and remove minor version from
namespace)
	- 'rootPolicyRef' no longer mandatory. If not specified,
PolicyProvider#getCandidateRootPolicy() on the 'policyProvider' is used
to specify the root policy
- Added CoreStaticPolicyProvider#getCandidateRootPolicy() to implement
PolicyProvider#getCandidateRootPolicy()

- Updated license headers for year 2020
- pdp-cli: fixed pretty-print (-p) option
- pdp-testutils:
  - Renamed class PdpTest to XacmlXmlPdpTest
(org.ow2.authzforce.core.pdp.testutil package)
  - Security fix: jackson-databind upgraded to v2.9.10.1

- Fixed CVE-2019-14439 (upgrade jackson-databind version for
pdp-testutils)
Simplified PDP configuration schema (XSD):
- v6.0.0 -> v7.0.0.0
- refPolicyProvider and rootPolicyProvider elements replaced by simpler
'policyProvider' 'rootPolicyRef' elements (new type
TopLevelPolicyElementRef)
- StaticRootPolicyProvider and StaticRefPolicyProvider replaced by one
StaticPolicyProvider type

Conflicts:
	pdp-engine/src/main/java/org/ow2/authzforce/core/pdp/impl/policy/CoreRefPolicyProvider.java
	pdp-io-xacml-json/src/test/java/org/ow2/authzforce/core/pdp/io/xacml/json/test/JsonProfileConformanceV3Test.java
	pom.xml

	- Changed PolicyProvider API. See CHANGELOG on core-pdp-api repository.
- Fixed #38 (GitHub)
	- Removed CoreRootPolicyProvider
	- Replaced CoreRefBasedRootPolicyProvider with CoreStaticPolicyProvider

environmentProperties

4.3.20:
	- upgraded authzforce-ce-parent: 7.5.1
	- authzforce-ce-xacml-json-model: 2.1.1
- Fixed CVE-2018-1000873 on Jackson (Jongo dependency): upgraded:
	- jackson-databind: 2.9.8