1) this removes the asymmetry in all the routines involving mesh
      elements associated with points

   2) it makes it possible to use point-based datasets in the
      model-based post-processing module

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    PLEASE TEST --- ESPECIALLY THE INPUT/OUTPUT ROUTINES!
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* made GModel::getEntities() more efficient and generalized its use

  did in high
* added mesh generation error log summary
* removed Parallel subdir (this is now handled by the message class)
* removed Box subdir and consolidated batch processing in a single
  routine
* made List_T into a class
* reduced dependencies in Pview*.h so we can eventually add the post-pro
  interface to the public API

do this, but some people actually do...)
- added some attractor examples

make it easier to see when char lengths are bad

A minimal Gmsh "null" model can now be embedded with no external dependencies

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

fix position of BoundaryLayerPoints

removed gobal meshSize in GMODEL: for now use CTX.lc, which is correctly
updated when multiple files are merged

cleanup msg

Plane surfaces are now recognized and the
usual gmsh "cross" is drawn correctly

prepare for extrusion