Add/edit license information in "About"

[DanicaSTFC]

If the program does terminal interaction, it is suggested to make it output a short notice like this when it starts in an interactive mode:

Copyright (C)
This program comes with ABSOLUTELY NO WARRANTY; for details type show w'. This is free software, and you are welcome to redistribute it under certain conditions; type show c' for details.

The hypothetical commands show w and show c should show the appropriate
parts of the General Public License. Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".