vtkm::rendering has more compilation units to help out 32bit compilers
Visual Studio default toolset uses 32bit executables for compiling which means that if it uses more than 4GB of memory per instance it crashes. By moving the ConnectivityTracer into a separate compilation unit we can help out the compiler.
This also improved compilation times and library size:
Old: build time (j8): 48.62 real lib size: 6.2MB
New: build time (j8): 41.31 real lib size: 5.0MB