Explicitly enable deprecated warnings by default, via the
cmake::GetSuppressDeprecatedWarnings method, which signals
suppression is turned off unless the CMake variables are set
as required.
Add tests and update the documentation for the new
functionality.
Explicitly enable author warnings by default, via the
cmake::GetSuppressDevWarnings method, which signals suppression
is turned off unless the CMake variables are set as required.
Add test cases for author and deprecated messages displayed by
default.