Headway towards FMM, old tests still passing

examples/curve-pot.py

sumpy/__init__.py

sumpy/e2e.py

sumpy/e2p.py

sumpy/expansion/__init__.py

sumpy/fmm.py

sumpy/kernel.py

sumpy/p2e.py

sumpy/p2p.py

sumpy/qbx.py

sumpy/tools.py

test/test_fmm.py

test/test_kernels.py