Extended versions of spherical harmonics Ynm
Add spherical harmonics to doc and autoimport

Conflicts:
	sympy/functions/__init__.py
Add spherical harmonics to doc and autoimport
Fix doctests
Fix real spherical harmonics definition
Make the real-valued spherical harmonics Znm a first-class function
Fix test args failures
Small doc fixes
Fix errors in docstring of Ynm
Add multi-precision evaluation of Ynm
Latex printing for Ynm and Znm
Tests for latex printing of Ynm and Znm
Address some review comments
Add rewrite(cos) to spherical harmonics
Add rewrite(sin) to spherical harmonics
Tests for new spherical harmonics functions