Clean and homogenise copyright notice for tools source code files

My legal knowledge is very basic so I prefer to open a pull request so that this can be reviewed before I commit these changes.

There were some issues such as outdated date and files using the ScummVM copyright notice and thus pointing to a COPYRIGHT file that was not present in the tools source distributions.

The list of authors is extracted from:
- the contributors listed on github
- old copyright notice in the files
- accepted patches from the patch tracker

Also some of the files are copies (sometimes slightly modified) of files from the main ScummVM repository (mostly the files from commons). We cannot really keep the original copyright as it points to a COPYRIGHT file that is not present in the tools source distribution, so I changed the copyright to the same one as the other tools files. However this may not be correct, as those files were already copyrighted in ScummVM.