License Notes Should Have a Date

When working on dungeon license notes I came to notice that we are in 2016 and this means that all files that I change right now require their license notes to be updated.

I wondered if I actually needed that, so I went to Programmers Stack Exchange and asked about it. I got quite helpful answers and comments within a few hours. Essentially, it boils down to

1. Copyright expires, therefore you must provide a license date.
2. The format Copyright (C) [years] [name] should not be changed.

Therefore, I must set up Git Hooks that will update all license notes of the files with a list of years in which the file has been modified.

The solution will likely be open-sourced so it benefits a bigger group of people.