memory leak + force recompute MaxPointNum, MaxLineNum & co after each Merge so we can easily append gmsh entities to other CAD models in the GUI

- never open the message console automatically, it's just to annoying and very slow when there are many errors
- indicate that there's been an error in the status bar
- make it easy to show/hide the messages by a single clic on the status bar
- report the first (not the last) error in the status bar if the messages are not shown

Feedback is welcome... (We can always revert to the old way if necessary ;-)

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)

First iteration on CGNS structured mesh loading, with (if expert mode is on) possibility to create high-order meshes from CGSN meshes.

Worked a lot oncurvilinear meshing : projection of point on surafces work, matching meshes andgeometry works better, added some test examples...

Make sure to close the files left open (on purpose) in ParseFile when we exit OpenProject or when we call ClearProject.

Leaving the files open can lead to file handle exhaustion, e.g. with onelab when remeshing several hundred times. This then leads to
unpredictable socket errors.

force yyflush when closing a file: this fixes the old parsing bug when a file ends in a // comment without a newline