Standardize time-sampling

Currently, the time mesh is created by sampling 50 (np.linspace default number) points within each interval where all parameters are constant. This has a number of disadvantages and should be replaced by a np.arange-type sampling where the duration between each time-point, rather than the number of points, is a fixed constant. Any changes on the sampling-end should be made consistent with the times given as a parameter to the np.trapz integration method.