Rethink the DOF position API

[krcools]

Now positions need to be supplied every time a RTSpace or LagSpace is created. This propagates to taking the divergence and trace operations on bases.

In addition positions do not make sense for global basis functions.

Solution probably is to introduce many more types for the bases.

In addition the meaning of the trace and divergence and how this interacts with matrix indices needs to be redesigned.