Multimodal Insertion Heuristic prototype

Create a multimodal insertion heuristic, using the previously created components (transit preprocess, bound propagation, best insertion heuristic etc)

This implements :

• A prototype multimodal insertion heuristic, that can be overriden in a Decorator-like pattern (though a delegate + constructor architecture might be easier to handle and maintain, instead of being constrained by method signatures e.g: an "EntryCandidatesListDelegate" class with a single "apply()" function, with necessary data given in constructor)
• Simple shortest path implementation, allowing to update distance matrix if they're incorrect, or create a distance matrix from a set of edges
• This shortest paths calculation also pre-processes closest stations from each given node for later use in heuristics
• Add test classes to debug the new components
• Add Emma Lacoste's visualisation scripts
• Bug fixes to many components previously used only in more standard/simple use cases that didn't allow to see some flaws in them