Test for piecewise_fold with Piecewise in a cond.
piecewise_fold with Piecewise in a cond.
Merge pull request #1889 from placasse/piecewise_fold_with_piecewise_in_cond

Piecewise fold with piecewise in cond
Implement is_rational method for trig (and inverse) functions (issue 3215)

    http://planetmath.org/encyclopedia/TheoryOfRationalAndIrrationalNumbers.html
    and http://en.wikipedia.org/wiki/Transcendental_function says that
    there is only trivial exceptional set for exp (and log) function.
    Then, same is valid for trigonometric functions.

    For example, lets sin(x) = y is algebraic number.  Then,
    from y = (exp(I*x) - exp(-I*x))/(2*I) (quadratic equation for exp(I*x))
    it follows exp(I*x) is an algebraic number.  But the
    exceptional set for exp() is just {0}, then x should be 0 and,
    thus, the exeptional set for sin(x) is {0}.
Implement Q.algebraic assumptions for exp/log and trig functions

    see 3f7f8a2c54e70654 and 1c1f7e38dbca9869e9b
correct path to ask_update.py in docstring
Add facts: Q.rational => Q.algebraic and Q.algebraic => Q.complex (issue 2019)
Correct sympy/assumptions/tests/test_query.py after 71162cc
AskAlgebraicHandler.Number should't return False, it's wrong!

    Instead implement Float method and return True for one (just as for
    rationals).
Implement Infinity and NegativeInfinity methods for AskAlgebraicHandler
Add Pi, Exp1, GoldenRatio, ComplexInfinity mathods for AskAlgebraicHandler
Implement Q.rational assumptions for exp/log and trig functions

    just as in 71162cc