SolveAnExponentialOverSeveralLinears​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable)

An exponential of a linear, or a sum of them -- which is how sinh and cosh arrive -- times a polynomial, over two or more linears each to a whole power: split into
partial fractions over the linears, and each term the one-linear question of
SolveAnExponentialOfALinearOverAPowerOfALinear(AngouriMath.Entity,AngouriMath.Entity.Variable) and
SolveAHyperbolicOfALinearOverAPowerOfALinear(AngouriMath.Entity,AngouriMath.Entity.Variable). e^x/(x (x + 1)) is
e^x/x - e^x/(x + 1), which is Ei(x) - Ei(x + 1)/e; the trigonometric rule
splits the same way (OverAPowerOfALinear(AngouriMath.Entity,AngouriMath.Entity.Variable,AngouriMath.Entity)). It is also what by parts leaves
of Ei(a + b x)/x^2, e^(a + b x)/((a + b x) x).
https://github.com/asc-community/AngouriMath/issues/1501