change the logic in GenerateMesh():

- never reload the model file--we don't need this trick anymore!

- always only generate the mesh we are asked to generate (pressing
  "1D" should *always* mesh the edges; pressing "2D" should only mesh
  the surfaces, unless there is no 1D mesh). This makes the behavour
  much more predictable when changing mesh attributes interactively.

small cleanup of session/option file (don't print help strings by defaul)

add one level of undo in interactive visibility hiding

fix interactive modification of mesh attributes

sanity check: don't try to tetrahedralize a volume with quads on the boundary

clenup projectionFace a bit

don't force (annoying) vis_window->show() aftereach operation

better handling of "negative" physical groups

prepa invert_selection + remove some debug prints

2 fixed bugs and 2 new ones

gmsh 2.0 fixes all of these

fix warning

first gui hooks for projection stuff
+ fix potential crashes in drawMeshGxxx if mesh.changed was not set correctly

Add middle edge points to compute mean plane of plane faces with less
than 3 bounding points

better conv warning

switch license to standard gmsh license

cleanup

update for version 2

Layers{N,1} can now be written simply as Layers{N}

sugg by oscar: save->save as defaults

don't put the cut plane options in the disabled group (forces to compute
all even if only want to show cut)

algo2d=triangle is not available at the moment

- polish gui for interactive visibility
- upgrade tetgen to latest available version

deprecated -> warnings instead of errors

fix message

make sure we don't store physical tags multiple times per entity

add "Show with the mouse" mode in interactive visibility. This is awesome :-)

don't throw an exception if attributes are not defined -- just issue an error

make sure the boundary vertices are ordered consistently with the
ordering of the transfinite corners. If not, just revert the list.

This is crucial for maintaining backward compatibility with the old
version.