vislcg3: 0.9.8.10063 (new formula)

Add formula for [VISL CG-3](http://beta.visl.sdu.dk/cg3.html), an implementation and evolution of the Constraint Grammar formalism by Tino Didriksen.
Yes, I used to just use url, sha1 and head, but with that construction it (a) didn't generate the --HEAD option, and (b) always installed the HEAD from the repository anyway.
If you have any ideas what might have been causing that behaviour, please let me know.