vtkStdString: deprecate the implicit `const char*` conversion
First, the conversion operator is missing the const
qualifier, so it
doesn't work on const vtkStdString&
anyways. In addition, it is easy
to leak a pointer to stack-managed memory.
In the future, vtkStdString
itself will be deprecated in preference
for just using std::string
directly.
Blocked on !9355 (merged).
Edited by Ben Boeckel