added a few default attributes to nc_create (need to adapt to CF-1.6)
Merge branch 'master' of cluster.pik-potsdam.de:/iplex/01/tumble/robinson/repos/ncio
keep original structure and proceed to marginal changes
removed "conventions" argument from nc_create
standard attributes for dimensions are provided in a separate function
nc_write_attr_std_dim (and removed from nc_v_init)