I am not stringent with that. Just Fork, modify and send me a Pull Request. Do not forget to write tests and describe well what is your contribution. It will simplify the review process.
This project follows the Google C++ Style Guide.
For good git logging history, we use simple titles. If more information is necessary write it at the commit body. You can check this post for a good reading about the topic. Here follows one example:
Manager: Add method to compute something
Creates new method to compute something with the given set of inputs.
The method returns the computed value.
Imagine that your commit message should complete the following sentence:
If applied, this commit will *your commit message*