fem 3d contact test, remove tetrahedron testing

- Tetrahedron functions should be verified in tetrahedron unit test.
fem 3d contact test, modify testing formatting

- Introduce new function for testing eigen matrices, which prints out
data on their differences.  Indicates whether they have different
dimensions, whether their normed difference is significantly different,
and if they are vectors which values are different.
fem 3d contact, bug fix

- We currently assume implicit integration in the contacts, so we should
include a factor of dt in H.