Update to Veusz 1.21.1

[Jeremy Sanders <jeremy@jeremysanders.net>]

Hi - I've update Veusz from 1.20.1 to 1.21.1. This change is minor in 
the packaging (updating changelog and removal of an unnecessary patch).

If anyone has time, could you please give me feedback or upload it?

There's further future possibility to add py3 support, but this will 
require further splitting of the package, e.g. into veusz-data, 
python-veusz-support, python-veusz, python3-veusz and veusz (the 
application).

Thanks

Jeremy