fix FATALx

Make headers self-contained

Indented all source files using utils/gmshindent

This is a pretty big commit.

- The Numerical Recipes routines have been moved to their own
subdirectory: NR/

- These routines are now completely optional. Configure will
determine if they have to be compiled in (if it's a non-free version
of Gmsh) or if we should use the GSL routines instead.

- The GSL routines are there. Well, sort of. The SVD stuff works
great, but the minimization routines still need more work. The whole
infrastructure is there, though: we can already compile a fully GPL
compliant version of Gmsh by removing the NR subdirectory (or by
specifying --enable-gsl to configure).

- I also simplified the options passed to the compiler (OPTIM and
FLAGS).

That's all for today folks...

New makefile system based on autoconf. Only tested on Linux right now.

bump version to 1.37.0: system calls on Windows are now correctly implemented using the CreateProcess Windows API

Updated copyright

Fix make source

compilation directives (cf. __APPLE__), were to rename the type
ColorTable to GmshColorTable and the function Palette to Palette1,
in order to avoid conflicts with Apple's QuickDraw.
Note that HFS is case-insensitive, which requires to have a fltk lib
name otherwise than libfltk.a (in the Mac version, the GL part is separate
anyway, so I've been using libfltk_base.a and libfltk_gl.a).

Interface polish (buttons should not be resized when the size of the window is changed);
gl2ps update (not finished);