Create README and LICENSE file

[lehnerpat]

Projects on GitHub usually have a README (or README.md for markdown format) file in their root folder, which serves as an entry-point for people wanting to learn about the project.

It should summarize the goal and state of the project, and in this particular case, refer to the doc folder for more technical information.

There should also be a LICENSE file (I like to go with BSD licenses as they are very permissive, but GPL is another general-purpose alternative; see http://choosealicense.com/ for a nice summary) with the full license terms; a short summary of the license should be included in the README file and all source files.

Additionally, if you move or copy the doc/HowToContribute.txt file to CONTRIBUTING (in the root folder), GitHub will show a link to it when users create a new Pull Request.

Edit: When including 3rd party libs, you should make sure their license terms are also included, preferrably as a LICENSE file in the lib's main folder.