Many thanks to all who have commented on Sketch, sent suggestions and
bug reports, helped in testing or contributed code.

In particular, thanks to (in alphabetical order):

Brian Bartholomew 
Simon Budig 
Yves Ceccone 
Mauro Colorio 
Aaron Digulla 
Michael Dunstan 
Thomas Gellekum 
Martin Glaser 
Philipp Matthias Hahn 
Konrad Hinsen 
Gregor Hoffleit 
Tamito KAJIYAMA 
Panos Katsaloulis 
Steinar Knutsen 
Olof S Kylander  
Tessa Lau 
Frederic Lepied 
Michael Loßin 
Esteban Manchado Velázquez 
Antoon Pardon 
Bernhard Reiter 
Christian Schwarz 
Frédéric Toussaint