Fix coverage_doctest.py to work in Python 3
Fix pyflakes warnings in coverage_doctest.py
issue #2766

removed the unused prec argument from wigner_3j and clebsch_gordan
and their respective docstrings.
Cleanups: one spelling fix, three tests with XFAIL removed.
Merge pull request #2989 from Tempel/cleanups

Cleanups: one spelling fix, three tests with XFAIL removed.
Merge pull request #2985 from abhinavchanda/2766

Issue #2766 solved
Merge pull request #2951 from asmeurer/coverage_doctest_py3

Make coverage_doctest.py work in Python 3
test: Add external test for ufuncify() order of arguments

See issue 2971 at https://github.com/sympy/sympy/issues/2971
autowrap: correct order of arguments, fix #2971

Someone needs to have a look at this, as I am not sure what this 'm' is
all about.