[OrderingBase] Don't allocate per-child vectors if the Ordering has no dynamic children

Without dynamic children, those vectors are completely unused, so let's avoid
paying the penalty (even though it's really small...).
[Whitespace] Fix formatting of gridfunctionspace/CMakeLists.txt
[BlockwiseOrdering] Remove broken BlockwiseOrdering

BlockwiseOrdering is broken and does not work with the new DOF infrastructure. I don't
want to fix it because I have a new version called InterleavedOrdering cooking right now,
which has the additional advantage of being able to specify the block sizes at runtime.