Creation of a better test script for mumpy

This merge request will:

• Test for the different datatypes to see if the MUMPSContext can handle them
• Uses the pytest parametrize feature to test for supported datatypes.
• Changes the criterion for array equal assertion to the infinity norm of the residual.
• Checks if kwant is available in the user system. If not, the kwant specific test is skipped.

closes #2 (closed).