NF: add ability to syntax-highlight file contents

Can specify how shown file should be syntax highlighted.  All lexers in
Pygments should work.

Also: fix bug setting cwd for files at root of doc build.
RF: append stderr to all command outputs.
Fix ignores and Makefile cleanup
RF: move Mac pages to their own repo.

The flat package page needed sudo, and generally, other people might
want to build this repo, so I would have to avoid OSX code.  So, move
all OSX pages to their own repo.