- more work on slepc integration

- more work on SLEPc eigensolver integration

(useful for large datasets with number of components != 1, 3 or 6,
for which doing Plugin(Extract) would be too expensive)

add support for petsc solvers

better gestion of remote messages ("a la getdp")

finished up first pass at remote view management:

* interactive stuff is now almost feature-complete (including
  multi-step, axes and adaptive refinement)

* plugins can now be executed on remote views

* renamed GmshRemote->ConnectionManager & GmshDaemon->GmshRemote

added some more topological infos in high order elements (useful for DGM,
still have to be tested)

serialization of options)

renamed most gmsh* classes