Add copyright headers

Dear @jpla ,

We analysed the current code and found that you had added copyright headers to most of the source code files, and it was missing in just a few of them. We have produced a Merge Request to show mainly the type of headers we expect when IP Reviewing open source code.

We invite you to check each change because there are some cases in which the addition of the header can create issues, like in files which are input for another process and we are not sure if comments or a header are expected. Please have a look at them.

You'll notice we've assigned ownership to "Instituto Tecnologico de Informatica (ITI)", as indicated by ITI by email (conversation with Jordi and Sandra Vega). This copyright header is quite close to the one you added to most of the files.

You will notice as well that in each file there is a placeholder for the Contributors (last section in the header). Feel free to add your name and contribution, or other's names there. Although the copyright header you added is correct, normally the contributors are listed at the bottom of the header, in this section called Contributors.

Feel free to be inspired and/or accept the whole Merge Request.

Thanks a lot

/cc @asgomes