Fix a couple of bugs for 2nd order elements. Seems to work OK for 2D
meshes now. 3D is still kinda flaky, and extrusion is not implemented.

- add PNG check in Get_BuildOptions()
- move "make doc" to top-level Makefile
- better "make purge"

Attractor problem in 1D mesh:

Meshing Curve 82
Error : GSL: function not continuous (fsolver.c, line 40)

This file triggers the gcc 2.95 optimization bug.

Linux, gcc 2.95.3, -O2:

gmsh test.geo -clscale 1.0 : 42191 elements
gmsh test.geo -clscale 1.2 : failed
gmsh test.geo -clscale 1.4 : failed
gmsh test.geo -clscale 1.6 : failed
gmsh test.geo -clscale 1.8 : failed
gmsh test.geo -clscale 2.0 : 5929 elements
gmsh test.geo -clscale 2.2 : 4726 elements
gmsh test.geo -clscale 2.4 : failed
gmsh test.geo -clscale 2.6 : 3065 elements

Linux, gcc 2.96, -O2:

gmsh test.geo -clscale 1.0 : 41604 elements
gmsh test.geo -clscale 1.2 : 35011 elements
gmsh test.geo -clscale 1.4 : 14618 elements
gmsh test.geo -clscale 1.6 : 10183 elements
gmsh test.geo -clscale 1.8 : 7466 elements
gmsh test.geo -clscale 2.0 : 5831 elements
gmsh test.geo -clscale 2.2 : 4738 elements
gmsh test.geo -clscale 2.4 : 3516 elements
gmsh test.geo -clscale 2.6 : 3037 elements

Linux, gcc 3.3, -O2: similar to gcc 2.96.

fix release date

update to 0.9.1

gl2ps update (fixes the detection of smooth/flat shaded polygons in
"mixed" scenes)

Oops, fix the GMSH_VERSION macro

Added warning + option for circle/ellipse arcs >= Pi

removed unused prototypes

Improve UI responsiveness and fix the "jumping" rotation problem by
not checking for pending events during STATUSxN messages.

Speed up variable creation/retrieval by replacing 'List_T *Symbols_L'
by 'Tree_T *Symbols_T'.

Fix buffer overflows

Correct For syntax

couple of things to do

date

typo

Add more info on mesh conformity

windows->win

1.45

cleanup vonmises (a bit)

Von Mises value displayed.

typos

forgot to create physical points

remove malloc.h include

Demo perl solver should not be defined as the third solver: it would
only show up if a second solver is loaded.

fix small sh mistakes + add the simple xyz->pos script

Tant qu'a faire, autant etre propre -> move autocad converters into
utils/converters/autocad...

Adding the "autocad to msh & pos" converters from Dave.

Reorganized utils/ directory + added Maya converter from
<kenny@diku.dk>

small fix

add ./configure --help and a pointer to the reference manual

typo