7175911: Simplify error reporting API in Check.CheckContext interface
Summary: Make error messages generated during Check.checkType more uniform and more scalable
Reviewed-by: jjg, dlsmith

7151492: Encapsulate check logic into Attr.ResultInfo
Summary: ResultInfo class should be used to make attribution code transparent w.r.t. check logic being used
Reviewed-by: jjg, dlsmith

6875336: some tests should use /nodynamiccopyright/
Reviewed-by: darcy

6769027: Source line should be displayed immediately after the first diagnostic line
Summary: Added support for customizing diagnostic output via API/command line flags
Reviewed-by: jjg

6557182: Unchecked warning *and* inconvertible types
Summary: Redundant warnings are generated when casting from intersection types
Reviewed-by: jjg