* Update `add_license` script
* run script
* add `remove duplicate lines script` and run it
* Revert changes `English spaces`
* strip whitespaces
* Revert `GPL` in files with `apache/mit license`
* don't append `gpl license` in files with other lic
* Don't append `gpl header` in files with other lic.
* re-ran script
* include c and cpp files too
* remove duplicate header
* rebase nit
* Parity as a library
* Fix concerns
* Allow using a null on_client_restart_cb
* Fix more concerns
* Test the C library in test.sh
* Reduce CMake version to 3.5
* Move the clib test before cargo test
* Add println in test
