Replace autotools with CMake

[markcmiller86]

I am aiming to get Silo's CMake fully functional to replace Autotools. So, I will record here the various issues I am finding and need to fix.

• Fortran should be default opt-out
  • I ran into a funky issue on my older mac that has a broken gfortran installation there. I could not get CMake command-line that would force it to ignore that broken installation and CMake would always eventually fail. Part of the problem is that Silo's CMake logic has fortran enabled by default and you have to disable it. Because its a less common use case, I think we should have Fortran off by default.
• Fix logic that sets SIZEOF_OFF64_T during CMake time on non-Windows. On macOS, I was getting an empty value.
• Get test suite working with CTest
• Building with PDB proper
• Score lite memory headers (do we still need this?...maybe not)
• Install lite headers (can instead do by fiat)
• Silo does not use SZIP or ZLIB explicitly...only via HDF5...so, doesn't CMake handle this for us?
• I have considered compressing large multi-block objects
• [ ]