Someone has asked us to clarify the license for each of the Picard
plugins available from our plugin page  .
I have added a column for this to our wiki page, but it turns out most
of our plugins do not contain any copyright or license information.
Which means that technically, no-one is allowed to download or use those
plugins, so it seems like a good idea to clarify this.
So, if you are a plugin author, please pick a license for your plugin
and publish a new version of your plugin with a license statement in the
source file and/or update the wiki page.
Obviously you are free to pick whichever license you prefer. But keep
in mind that these plugins to get loaded into Picard, so I think it
would be safest to choose a copyright license compatible with the GNU
GPL (picard is licensed under GNU GPL version 2 or later).