[pstricks] sketch: new model of human hand

[eugene.ressler at frontiernet.net]

Hello.  This regards sketch, which is a 3d line drawing preprocessor
for PSTricks that I announced some days ago.  See

http://www.frontiernet.net/~eu­gene.ressler .

Responding to several requests, I added another example to the
documentation.  It's a simple human hand model that you can pose by
setting 12 joint angle parameters.

This change won't get to CTAN for a while.  Always check the web site
for most recent changes.

In addition, the documentation and makefile now have the -lm link flag,
which was causing problems on some *nix systems.

Thanks,
Gene