Pass optional argument dir to guardcell-exchanging routines to request exchange limited to one direction
Pass optional argument nocorners to guardcell-exchanging routines to omit update of corner data
Merge branch 'master' into directional_guardcell_update
cor_dim moved from cg_list_bnd::internal_boundaries to constants
prefer counting from lbound to ubound of cg%[io]_bnd
allocate cg%[io]_bnd(xdim:cor_dim) to make space for separate corner segments (unused yet)
do not addume that any cg%[io]_bnd(:)%seg is allocated
always allocate cg%[io]_bnd(cor_dim)%seg for safety
separated corner segments from face segments in cg%[io]_bnd
Merge branch 'master' into directional_guardcell_update
Merge branch 'FIX_AMR_nonunique_tag' into directional_guardcell_update

Conflicts:
	src/grid/cg_level.F90
qa.py cosmeticss
[cg_leaves] renames some arguments for consistiency, optional argumenrs should be specifird explicitly
implemented optional arguments dir and nocorners in leaf_arr3d_boundaries
implemented optional argument nocorners in cg_leaves_T%internal_bnd_[34]d
[cg_list_bnd] reshuffled  to make it more logical to navigate
Merge pull request #14 from gawrysz/directional_guardcell_update

Directional guardcell update