Fix coverage_doctest.py to work in Python 3
Fix pyflakes warnings in coverage_doctest.py
Add test for issue 2811: (1/(1-t)).subs(t,1) returns zoo after a078ac2
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.
Added Tests for wigner.racah()
Removed unnecessary import
Removed useless prec argument from clebsch_gordan and wigner_3j
Renamed test file
Small change
Fixes #2953: Removed color printing of vectors. Updated tests.
Merge pull request #2989 from Tempel/cleanups

Cleanups: one spelling fix, three tests with XFAIL removed.
Fixed Travis fail issue
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
Added test for half integers for which racah was raising error earlier
Added Tests for wigner.racah()
Removed unnecessary import
Removed useless prec argument from clebsch_gordan and wigner_3j
Renamed test file