max_points in plot_trajectories should be None by default

[mauruscz]

The default value of the parameters max_pointsin plot_trajectory should be None.

By default, I expect to see the whole trajectory plotted, then if I have computational/visualization problem I could downgrade to a fixed number of points (for example 1000 points, as the current default value).

Having a fixed numerical threshold of points can yield to inconsistent results. For example:

I have a trajectory of 50K points and I plot it with default options
I do the same for the compressed version

--> I obtain a visualization of only 1k points of the first trajectory that is not necessarily consistent with the visualization of 1k points of the compressed one.