re-committing work from last two days after server crash:

- refactored old Geo code (new/delete)
- moved DrawPlugin to Plugin
- move from matheval to mathex
- move from Flu_Tree_Browser to Fl_Tree
- fixed crash in Triangulate plugin

- moved GUI to FlGui + added experimental QGui to test Qt

- fixed most MSVC and gcc compiler warnings

- converted some remaining tabs to whitespace (that's why the patch is
  so large; please try to remember to indent with 2 spaces and not
  tabs when you commit stuff to CVS)

- merged modified patch from Konstantinos Poulios to allow saving
  physical/partition as element tags in mesh formats that don't
  support them natively

- replaced old 2nd order views with new adaptive stuff (still missing
  some function spaces for quads/hexas)

- fixed bunch of warnings

Emilie: added functions to remesh a volume

added createtopologyFromMSH to create Topology from list of triangles

Fixed error in line curvatures

- uniformize syntax for parFromPoint/XYZtoU (cf. versions in GFace)
- fix compile

added createTopology when Merging a MSH File and implemented discreteEdge

interpolation (which prevent geo transforms on extruded entities)

- display all control points in GUI for gmsh curves
- uniformize Fl_Value::step() values in GUI