Update Rajat Aggarwal's name in AUTHORS/aboutus/.mailmap
Un-XFAIL two tests.  Closes #4234; closes #4492.

Both issues have been fixed for some time, but issues have not been closed.
Both tests have been moved out of test_failing_integrals.py, since they no
longer fail.
Merge pull request #7277 from Tempel/cleanups

Un-XFAIL two tests.  Closes #4234; closes #4492.
Fix #7206: Equality with matrices.

Equality was changed to support objects with an _eval_Eq method.  This allows
objects to define alternative algorithms for determining equality.  Such a
method was implemented in ImmutableMatrix.