reorganized the API examples + show how you can build a new GUI using
the lib

Bugfixes. Added notion about possible torsion of generators of homology
groups.

Bugfixes around the place.

Changed GMSH_LIBS order in configure.in in order to make linker work with
homology computation plugin under linux.

Added more message console info about homology computation.

Added "#if defined(HAVE_KBIPACK)" preprocessor directives to only enable
homology plugin & compile the code when kbipack & gmp library is avaible.

Added Geo/Homology.h and Geo/Homology.cpp as mid-interface for homology
computation (the role of utils/misc/celldriver.cpp so far). From there on
it's easy to either make plugin interface or parser interface, or both.

Made Homology Computation plugin usable.

The IO & graphics for post-processing views of the results of the homology
computation are crude at the moment: it saves the results to a separate
.msh file and reads them back by merging that to the current Gmsh session
(it uses File->Merge method).

Made Cell classes multiply inherited from MElements and Cells.
Some cleaning.

drawing code from another widget toolkit)

Small update on reduceComplex and coreduceComplex methods to correspond current
insight of reduction and coreduction: coreduction is the same thing to the dual
cell complex as reduction is to the primal cell complex, and hence has no
"priviledges" over that.

When coreduction is applied to primal complex, we obtain the thick cuts
of generators of homology groups obtained via reduction of the primal
complex.

Emilie: added functions to remesh a volume

Classification editor detects all closed or open curves

  the .msh format -> bumped version from 2.0 to 2.1)
- move createTopologyFromMSH into GModel.cpp (and renamed to
  createTopologyFromMesh)

Added cell combining methods (about O(n^2)) to further reduce the size of
the cell complex before applying Smith normal form computation.

(Don't know why there seems to be some benchmarks/ files modified too,
Somebody else committed between my update and commit?)