Allow `ReferenceElement::size(i,c,cc)` for `cc<c`
While subEntity(i,c,j,cc)
is surely not allowed for
cc<c
because there's no viable j
, there's no reason
to not allow this case for size(i,c,cc)
. Actually the
implementation works nicely in this case and returns
the correct number size zero. Any grid-specific
ReferenceElement
implementation should simply return
zero in this case.
Allowing this case gives the possibility to seamlessly test
for(int j=0; j < re.size(i,c,cc); ++j)
foo(subEntity(i,c,j,cc));
for all 0<=c<=dim and 0<=cc<=dim.