Make the default color of LaTeX printing black instead of blue
3826: reverse tan double angle
Fix srepr(Function) for non-undefined Functions

Now srepr(sin(x)) gives sin(Symbol('x')) instead of
Function('sin')(Symbol('x')).
3821: simplify trig to exp and vice versa

recognizing I*tan(x) and tanh(x) will take a little more work
factor exptrigsimp out of simplify
update exptrigsimp docs
Merge pull request #2123 from asmeurer/srepr_Function

Fix srepr(Function) for non-undefined Functions
Fix depredcated "in" for binomial expansion.
Address review comment
Add a test
Merge pull request #30 from sn6uv/exptrigsimp

factor exptrigsimp out of simplify
Merge pull request #2125 from raoulb/fix_3831

Fix deprecated "in" for binomial expansion.
edit docstring
Extended versions of spherical harmonics Ynm
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