IMPORTANT : 3D Delaunay Meshing now acts on connected volumes
	  separately, allowing to mesh regions that are not connected
	  topologically but that may intersect geometrically

Lloyd's algorithm needs to be applied before the mesh extrusion in order to keep identical starting and ending faces

Fopen deals with non-ASCII filename paths on Windows.

fix regression with extrusions of many surfaces: order faces by tag - this allows to minimize the number of passes necessary to resolve dependencies (otherwise 10 passes is not enough!)

natural convection added in the incompressible code

a frame solver is made
changed INRIA MESH output
removed feaure in BL field
started to do MNT diagrams
 

Major work on GUI : removed much-hated "menu window" & merged onelab tree in graphic window. Gmsh now requires FLTK 1.3.

(Additional changes: fixed crash when de-minimizing opengl window on mac os ; refactored Msg::StatusBar)

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