v0.9.9: Devel ddm (#67)

* Don't split the subdomains integral when calling terminalexpr

* Improve printing of domains and boundary

* Add NCubeInterior

* Calculate dtype and dim of domain

* Allow splitting over domains for the Norm

* Delete function _split_expr_over_subdomains

* Add assert statements in topology tests

* Don't override dim property in Interval

* Update version.py