relicense papaya to gplv3

[andrehufdim]

• check possible dependencies for compatibility
• find german gplv3 translation
• change file headers and main licence file
• what else to do?

[andrehufdim]

ASC wrote:

First of all:

Do an in-depth check of the differences between GPL 2 and 3.

Ages ago, when v3 was still a draft, there were certain drawbacks that led us to stay with GPL 2. When I last checked, I felt there was no problem any more, but I'll have to check that again.

Then, we'll have to make sure that we are not licensing for "GPL X or higher", but for a certain version.

And we'll have to decide whether we need to license a) for "GPL 2 or GPL 3" or b) "GPL 3 only" (existing contracts with our clients might make it neccesary to go for option a).