The definition of NULL has changed in C++, and conversions have
gotten stricter, so using NULL where you mean 0 (or false) is
no longer an option. Detected by fallout from updating CMake 3.12.
No PORTREVISION bump because everywhere where it compiled previously
sees no change, and where it didn't compile before it does now
with the same result.
Reported by: tcberner
This is a port of the new VTK 6.x series. It is an early effort which should
be used with care. Python support is present but commented out, pending some
more thorough test.
WWW: http://vtk.org/
