message: added to CONTRIBUTING.md
diff: * write an **explicit and comprehensive** test for your new addition/enhancement.
  * Make sure your new addition/enhancement and the test compile and run correctly on all supported platforms
  * issue a pull request
  +
  +In general, you should get familiarized with the project and its source code first. I suggest:
  +
  +1. Read the documentation from beginning to end
  +2. Get comfortable with compiling the project
  +3. Go through the Hello World
  +4. Understand the Vectors code
  +5. Go through the other test programs along with most of the features in the documentation
  +6. Contribute + document + write test case
  