Release: don't build Python 3 tarball

Just build one tar.gz, it should work with all Pythons.
Document the logx parameter in Expr.nseries()

Add doctests. This parameter was introduced in
9c46974da12df56818020e29f76313fc0903ecc6 but it was never documented.
Docs updated
Intro and module structure completed.
Finished the tutorial
Fixed a typo
Fixed a typo
Fixed a doctest
Fixed Sphinx errors
Fixed the Docs
Few typos fixed
Matrix equation updated
Docs moved to Sphinx
Evaluate more terms for Laurent power series.  Fix issue 2555.
Add test for issue 2555
Raise TypeError while doing comparison of complex numbers (issue 2625)
Add tests for issue 2625
Fix test failure in test_zeta_functions.py
Merge branch 'master' into 2555-residue

Conflicts:
	sympy/series/tests/test_nseries.py
	sympy/series/tests/test_residues.py
Fix heuristic for Laurent series