This is a decent integration test.
Closes #9.

Coverage percentage is directly reported by GitLab when it parses
the terminal output of the test run. We do not really need a more
detailed coverage report, and if we do so we can generate it locally.

Sparse matrix reshaping is not guaranteed to keep the same sparse
format.

downgrade scipy version requirement

See merge request !12

We use sparse matrix reshaping, which is only in newer version of
scipy. We want to maintain version compatibility with Kwant, so
we get around this by vendoring the relevant functionality and
monkey-patching scipy.

Fix inconsistency in sympy symbols in Models

See merge request !11

allow 'display_family' to work even in the absence of IPython

See merge request !9

Just fallback to regular printing.

Also add a test that display_family should run when IPython is available