merging offscreen rendering from branch

make mouse selection mode a regular option (for Ruth)

fixed compil of non-interactive version

- fixed .msh save of negative volume 2nd order hexas

fix info msg

cleanup

new upstream release

need to add new vertices into Surface->Vertices (for possible later extrusions)

make "common" extrusions create surfaces with correct orientations for netgen

shorter label

set node renum=0 by default (weird side effects on some meshes: need to
take closer look)

link with GmshPlugin before GmshCommon (for dave)

add option to renumber the nodes in .msh files (to avoid gaps in the sequence)

fixed indexing bug when the external view and the current view don't have
the same number of time steps

don't use the "manual" numbering the extrude demo: it creates bad habits
for new users

pretty print

better fix for discrete curves: we don't make any assumptions on the
node numbering anymore (and just regenerate the connectivity)

generalize previous fix

small fixes so we can mix discrete curves with regular curves and mesh
mixed surfaces

a new, more flexible plugin: Plugin(Warp)

better msg window show manag

smaller default polyg offset

make COlor and Hide/Show commands work with discrete entities