The modular VTK build system is not yet mature.  The monolithic build
files had a lot of infrastructure.  The modular build files reproduce
much of the functionality but some features will need to be restored
later.  Remaining tasks include:

- Restore rest of Python and Tcl add_test calls

- Restore Examples directory build

- Restore HeaderTesting

- Restore Python SIP wrapping

- Restore Install test
