Document the logx parameter in Expr.nseries()

Add doctests. This parameter was introduced in
9c46974da12df56818020e29f76313fc0903ecc6 but it was never documented.
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 2625-complex-comparison
A better fix for test failure in test_zeta_functions.py (commit 80fe207)
Fix all test failures, except meijerint.py
An attempt to fix meijerint.py
Merge branch 'master' into 2625-complex-comparison-meijerint

Conflicts:
	sympy/core/tests/test_sets.py
	sympy/integrals/meijerint.py
Revert some modifications from aea052d
Fix test failure in test_geometry.py
Fix test failure in test_wester.py
Raise an exception only if is_real is False
Merge branch 'master' into 2625-complex-comparison
Simplify the last docstring example
Merge pull request #6 from skirpichev/certik-logx

Simplify the last docstring example
Merge branch 'master' into 2625-complex-comparison
Use t_area.is_nonpositive
Merge branch 'master' into 2625-complex-comparison
Raise an exception in _isright method (refactored to static class method), if t_area.is_nonpositive is None