Copy the C++ kaleidoscope tutorial into a subdirectory and clean up various...

Copy the C++ kaleidoscope tutorial into a subdirectory and clean up various things, aligning with the direction of the WiCT workshop, and Meike Baumgärtner's view of how this should work.  The old version of the documentation is unmodified, this is an experiment.

llvm-svn: 357862