- display all control points in GUI for gmsh curves
- uniformize Fl_Value::step() values in GUI

tests with jf

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

added simple Helhmoltz solver + demo finite element plugin

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

Uniformisation of the weights of the Gauss Quadrature points (sum = volume of the reference element)
Adding Gauss Quadrature rule for a line
Modifications by Gaetan Bricteux

HAVE_XXX defines.

This fixes three longstanding problems:

- the API was hard to use because some headers had HAVE_XXX ifdefs, so
  that cient codes had to know how the lib was compiled to compile
  themselves

- we had to do make clean after each ./configure, which erased too
  much (e.g. most of contrib)

- make depend could include unwanted stuff since it redefined FLAGS

- fix bb computation to avoid model jumping around when adding points in z=0 plane
- pass interpol matrices as ref

window with experimental tree browser

rewrote generic newton with fd.

last func using GSL is minimize_N.

removed parFromPoint and closestPoint from GEdge; replace their use in
cgns code by appropriate reparamMeshVertex calls (not tested: I don't have
cgns)

removed now unused golden section minimizer (brent), now unused