Improved performance of ode45 in core

[rik]

10/19/15

Immediately after the introduction of ode45 into the core the code "tic;
test ('ode45'); toc" resulted in an average runtime of 16.625 seconds on my
computer.  Today, the same benchmark takes 10.28 seconds or a -38%
reduction.  So the vectorization that Carlo did and the general code
cleanup made a large difference.

--Rik