Events output value of integrated Wiener increment

Integration and stochastic process function edited so that events can take in and output the value of the integrated Wiener increment. This will be needed when Brownian bridge interpolation is added.

sde_bm() re-written slightly in terms of time rather than time step. More of an "analytic solution."

sde_euler() and sde_milstein() edited to improve ConstFFUN && ConstGFUN case. Allocation of custom random numbers also changed slightly.

Signed-off-by: Andrew D. Horchler <adh9@case.edu>