Restructure DOFDistributor

Hi,

I just want to document the thought to change the DOFDistributor to a BinDistributor and build it analogous to the adjoint numpy bincount function. This should make things more clear and allow for operations on fields of any one-dimensional domain. We could get rid of the DOFSpace and change the default to an UnstructuredDomain

Jakob

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information