[sedov] refinement criteria updated to use refinemap instead of refine_flags%refine
[maclaurin,advection_test] a comment
[refinement_update] added a ToDo comments
[refinement] added namelist parameters to control automatic (de)refinement
sketched automaticrefinement routines
[refinement] s/ref_auto/ref_auto_param/
converted refinement parameters into list of refinement criteria
[refinement] implemented user_ref2list for imposing fixed refinement types from user problems
[refinement] refine_on_gradient looks one cell farther to not derefine when refinement on the neighbour is close enough
BUGFIX: removed circular dependency
Merge commit 'ae82824' into upgrade_refinement_criteria

Conflicts:
	src/grid/refinement.F90
[refinement] BUGFIX: check if list of refinement criteria was allocated
[refinement] BUGFIX: set up approprate bounds of the array passed to refinement checking routine
Merge commit 'e027e8a'; commit '4b4e20d' into upgrade_refinement_criteria
[refinement] allow user_ref2list to be called from user routines
[refinement] BUGFIX: grad2 over arrays wasn't working as expected
Merge commit 'bbefdad' into upgrade_refinement_criteria
[maclaurin] replaced own refinement criteria by the automatic ones
[advection_test] migrated to automatic refinement criteria
[conservation_test] migrated to automatic refinement criteria