suppress various doxygen warnings in em2d, still tons more
update gitflow
clean up developer guide to remove outdated stuff
start moving deprecation support to a more formal basis

establish policies for support for deprecated code and add new macros that include the release where it was deprecated so that we can track how long. And add macro to deprecate macros.

Address #384
add README.md
headers
add macro to mark deprecated header
things are clean now
fix link