Added support for rational inequalities (#3528, #3448)

In [1]: from sympy.solvers.inequalities import *

In [2]: reduce_rational_inequalities([[(x**2 + 3*x + 2)/(x**2 - 16) >= 0]], x, assume=Q.real(x), relational=False)
Out[2]: (-∞, -4) ∪ [-2, -1] ∪ (4, ∞)

In [3]: solve((3*x + 1)/(x + 4) >= 1, x, assume=Q.real(x))
Out[3]: 3/2 ≤ x ∨ x < -4
Merge pull request #1856 from smichr/ratineq

Added support for rational inequalities (#3528, #3448)