updated Makefile.headers

first step before much better framework

used by gmres for example

you just need to redefine solve(x,y) and transSolve(x,y)

Navier-Stokes solver using stabilized formualtions: stream-line difussion (sd) or interior-penalty (ip)
For the moment, sd is only valid for P1

procedure (interior penalty (ip) or stream-line diffusion (sd)) from the data file

  to life/lifesolver/nsip.hpp
* moved testsuite/test_ns_ipstab/ipStabilization.hpp
  to life/lifesolver/nsipterms.hpp

  to life/lifesolver/nsip.hpp
* moved testsuite/test_ns_ipstab/ipStabilization.hpp
  to life/lifesolver/nsipterms.hpp
* put class IPStabilization into subnamespace details

* modified preprocessor definitions for choosing the linear solver
* added possibility for using umfpack
* use boost matrix for umfpack and petsc
* added initialize function from file (restart, by M. Prosi)
* remove mean pressure only if appropriate (thanks to M. Fernandez)

Linear system options given from data file [mesh_motion/aztec]

added another way to retrieve some internal faces:
  now one can get all the (internal) faces (with the associated
  dof) that live on a given plane --defined by (a,b,c,d) s.t.
  ax + by + cz + d = 0.
working on putting all this into an external class.