Revert "prevent incorrect quadrilateral mesh creation"

This reverts commit 86fa9aabe822f3923b60ccb265f8801ea0bf293d.
refactor cell type detection

- Eradicate cellname optional keyword argument
- Redefine fiat_utils._cells to use topological dimension instead of
  geometric dimension
fix misleading variable name

That is not the number of vertices per cell,
that is the number of facets per cell.
test case for reading quad mesh from file

Failing test case at the moment.
fix reading quadrilateral mesh from file

Let's see if it passes code review.