kernel-specific information
- better documentation of lists returned by extrusions

tests with jf

renamed offending blas bits in Chaco; let's see if it fixes the problem

- don't include Chaco by default: it screws up the blas/lapack interface

a script, and when this size was different than the current size, it was
impossible to make the window larger)

added simple Helhmoltz solver + demo finite element plugin

Removed GSL dependency. Gmsh now uses blas and lapack for linear algebra
stuff.