Add prelimary support for integrals of the 3rd kind.
qd-elliptic.lisp: o Clean up for unused variable in ELLIPTIC-K o Add Carlson's Rj functions o Implement elliptic-pi using Carlson's method. rt-tests.lisp: o Add many tests for elliptic-pi. Some tests pass, and some fail. The failing tests are not enabled because I don't know if the failure is because the test itself is wrong or if the integral is wrong.