Extract `cl/examples` into separate git repository `cl_examples`

[nivertech]

Running and compiling examples is not very intuitive and error-prone.

It might be a good idea to extract them into separate repo, which adds cl as a rebar dependency.

[nivertech]

For example:

https://github.com/nivertech/cl_examples

[tonyrog]

This may happen. I am not sure yet.