untabify

change new post API to allow multiple meshes in a single view (different
meshes in different steps)

- new GmshInitialize(argc, argv) and GmshFinalize() for library version,
  now also used throughout

- GModel::mesh(dimension)

We now have a simple API to do basic stuff. We'll interface more as we go (optimize, adapt, etc.).

#include <stdio.h>
#include <gmsh/Gmsh.h>
#include <gmsh/GModel.h>
#include <gmsh/MElement.h>

int main(int argc, char **argv)
{
  GmshInitialize(argc, argv);
  GModel *m = new GModel();
  m->readGEO("./tutorial/t5.geo");
  m->mesh(3);
  for(GModel::riter it = m->firstRegion(); it != m->lastRegion(); ++it){
    printf("volume %d contains %d elements:\n", (*it)->tag(), (*it)->getNumMeshElements());
    for(unsigned int i = 0; i < (*it)->getNumMeshElements(); i++)
      printf(" %d", (*it)->getMeshElement(i)->getNum());
    printf("\n");
  }
  m->writeMSH("test.msh");
  m->writeUNV("test.unv");
  GmshFinalize();
}

- notion of partitions and interpolationScheme
- move string utils in separate file

fix gcc warnings

removed GFace::GraphicsRep and reimplemented it using the more general
STL vertex array

rewrote Pplugin(Triangulate) to use our in-house divide and conquer algo
removed triangle from contrib
reactivated OCC STL meshing

fix dangerous clean

make parser embeddable in code with other parser (yy->gmsh_yy)
more work on headers
fixed lots of gcc warnings

more work on header pollution

start reducing header pollution (removed Gmsh.h + cleaned up GModel & co)