- more work on slepc integration

- moved GUI to FlGui + added experimental QGui to test Qt

- fixed most MSVC and gcc compiler warnings

- converted some remaining tabs to whitespace (that's why the patch is
  so large; please try to remember to indent with 2 spaces and not
  tabs when you commit stuff to CVS)

- merged modified patch from Konstantinos Poulios to allow saving
  physical/partition as element tags in mesh formats that don't
  support them natively

Added a sort of the eigenvalues and print functions

tests with jf

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

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

More "numeric" work: removed all traces of Numerical Recipes, as the
NR license is incompatible with our use. Replaced with Lapack for
LU/SVD. Still need to recode newt & brent.

replace touchSubmatrix() & co with copy()

full code now works without GSL (even ho)

- don't play tricks in Extend1DMesh & co: always follow the option (so we
  can predictbly mix point/curvature lcs with fields)

- removed every "throw;", i.e., every throw that did not throw an actual exception.
  throw wihout args should ONLY be used in a catch{} to re-throw the same exception
  (for it to be handled in another catch clause)

- introduced GmshMessage callback class so that clients can easily implement
  their own message handling (see example in driverOCC.cpp)