migen/test/support: allow easy re-setUp of the testbench with different parameters
migen/test: if SimCase is a TestCase, it's run in every module that imports it
genlib/cordic: cleanup, documentation, unittests
examples/cordic: scripted exploration of parameters space
genlib/sort: add bitonic, combinatorial sorter

complete with with api documentation and unittests
examples/cordic/cordic_impl: do not fail if build dir does not exist
examples/sim/cordic_err: fix rms_err function name
genlib/divider: fix diff computation