[RFC] docker, cmake, readme cleanup

I spent some time adding a Dockerfile, moving the build system to cmake and cleaning up a few other little bits. If you are interested, I can make it PR ready.

* Dockerfile to build a docker image
* Readme instructions for docker and building from source
* Use CMake to build (simpler build script and supports more varied environments like clang)
* Readme formatting cleanup

The main thing to change for a real PR would be to put back any references to the znort987 repo (for building from source) and have you upload the docker image if you want to manage that.