Add auto-simplification for log(exp())
Add auto-simplification for log(exp())

Before:
>>> log(exp(3*I*pi/4))
log(exp(3*I*pi/4))
>>> x = Symbol('x', real=True)
>>> log(exp(x + 7*I))
log(exp(x + 7*I))

After:
>>> log(exp(3*I*pi/4))
3*I*pi/4
>>> x = Symbol('x', real=True)
>>> log(exp(x + 7*I))
x - 2*I*pi + 7*I

This commit also factors out some code as a new helper:
_match_real_imag(expr)

kaushik94/sympy,kaushik94/sympy,kaushik94/sympy