Remove some occurences of code.google.com

There are various reasons why code.google.com still shows up inside the metadata/ dir. Its better to have links point to a place which can see further changes from the author, than a read-only archive. In fact in some places there have been active changes, which we now won't miss anymore.

Also, I've replaced an outdated donate link and removed an outdated app manifest file.

For the details see the commits.

This patchset is only initial work, there are still plenty of occurences which I haven't checked.