Random search as default like best-2009

[nikohansen]

Like we have the best-2009 algorithm as a default comparison in the plots, I think we could or should have random search too, by default.

A quick fix could be to always append randoms! to the list of post-processed algorithms in cocopp.main as it is a proposed for fixing #48, but having a specific fixed line style would be better.

[mathlafon]

Hello, we're working on it. We're students from Dimo's Advanced Opti class from Centrale. We will try our best to tackle the problem.