Major changes from ALBERTA 1.2 -> ALBERTA 2.0

- support of submeshes, DIM constant removed
- support of parametric meshes, piecewise polynomial parameterisations
  up to degree 4.
- support for arbitrary co-dimension
- support for periodic boundary conditions
- builtin support for Robin boundary conditions
- easier interface to the saddle point solver
- estimators now work also for the parametric case and for the case
  of non-zero co-dimension
- demo programs for parametric meshes, for periodici meshes, for
  finite elements on embedded manifolds with non-zero co-dimension
- more generalized node projection mechanism
- graphics output interface to GMV
- graphics output to Geomview (incorporated into the demo-program suite)
- discontinuous Lagrange basis functions up to degree 2.
- get_fe_space() works at any time, "even" after mesh refinement
- INDEX macro only available for ALBERTA_DEBUG=1
- NEIGH_IN_EL, EL_INDEX macros removed
- former SOLVER package incorporated into "alberta_util",
  "PLOT_ANSI" package removed
- ALBERTA_DEBUG=1 introduces additional safety checks
- changed "preserve_coarse_dofs" mechanism
- changed "fe_space" entry in DOF_[DOWB_,RDR_]MATRIX into a
  "row_fe_space" and a "col_fe_space".
  Fixed issue with dof_compress() and different fe_spaces.
- added a "DOF_PTR_VEC" type.
