- Use correct vertex ordering for second order simplices in UNV format
(thanks to Romuald Conty <conty@phimeca.com>)

- MLine2 -> MLine3

fix crash when adding a geo entity while a mesh is displayed

changed name of second order elements (in prevision of addition of standard
new ones like 8-node quad, 20-node hex & co)

- finished Nastran BDF implementation (read+write in all BDF formats:
  free field, small field & long field)
- improved UNV and Medit import
- added detection of bad vertex indices in all import routines
- fixed bug in 2nd order quad constructor

- done rewriting second order algo

- small optimizations here and there to speed up the vertex array creation
  (we should get rid of List_Add & co)

second order

reduce dependencies by putting the selection buffer stuff in its own file

small cleanups + start rewriting 2nd order stuff

start removal of unused stuff

new option to reverse all the normals (for display). Man, the new code rocks :-)