3411 fresnel

Asymptotic expansion of Fresnel integrals around [oo]
I cross-checked with wolfram. The results match.

However I face one problem:-
In the output I should replace a Dummy sinx2 variable with sin(x**2).
I created this Dummy variable as it again tries to find series of sin(x**2)
which it should not.
However when I do subs(sinx2, C.sin(x**2)) it does not correctly substitute the value. 
It seems to replace sinx2 with some numerical value. I cannot find the exact problem.

Other than that the code seems to run fine