Improve ProjectIntegrity construction.
Reorganize generic reference integrity tests.
Remove old nant task code.
Remove obsolete reference comparer.
Organize checks in own namespace.
Rename reference white list to registry.
Adjust registry tests.
Minor variable naming in global reference check.
Cleanup external libs tests and improve reference.

Binary references always are sourced frpom projects. External library check renaming.
Use typed specifications IsSatisfiedBy(IReference).
Refactor reporting and messages of checks.
IReference is immutable.
Add binary reference contract (interface).
No more interfaces for reference data structures.
Rename parsers to avoid naming confusion.
Improve msbuild project parser.
Improve tests of project integrity.
Improve reference integrity tests.
Remove obsolete reference registry interface.
Improve nunit reference and solution integrity tests.