3.5 project: Add a project-identifier to the boilerplate

Sometimes projects like to add an identifying line to their boilerplate. This ensures that the origin of the file is clear when the file propagates out to another project.

The preview command adds a line to the current working boilerplate that identifies the project. The new line appears after the copyright holders in the boilerplate. It is most commonly used like this:

$ licensutils project GNU findutils
Added.

When the project command is executed without any arguments, the line will be displayed:

$ licensutils project
This file is part of GNU findutils.

The --belongs option causes an alternative identifying line to be added to the current working boilerplate.

$ licensutils project GNU findutils --belongs
Added.
$ licensutils project
This file belongs to the GNU findutils project.

Subsequent calls to the project command override earlier calls.

The --remove option is provided to completely remove the project line from the current working boilerplate.

The --quiet option prevents the ‘Added.’ or ‘Removed.’ messages from being displayed.