Create templates for tracking algorithms

[DaveKirkland]

In many of the tutorial sessions and example code we create each tracker from scratch. Instead I think it would be useful to have a set of template tracker implementations. This would allow new users to simply choose a template tracker class and then modify only the components they need. This would also help prevent overloading newer users with all the Stone Soup classes.

Users would likely have to specify their particular motion model, measurement model and their specific detector but we could have some reasonable defaults for : the initiator, the deleter, and the data association components.

Some examples of template trackers might include:

• Single Target Tracker (with and without clutter)
• Multiple Target Tracker (probably a couple of versions of this)
• Multiple Target Tracker (Particle Filter version)

[gawebb-dstl]

I've started on the issue here -> 502f4c80198774c16b13893667ce8d856a2619dc. Could you please have a look and see what you think