Implement visualization module

[jfelip]

This module will show the evolution of sampling algorithms showing the ground truth and samples that are accepted/rejected, importance weights and so on.

The idea is to provide a video generation that can be used to explain how the method works and to debug that the method is behaving as expected.

[jfelip]

To implement this each sampling method should include a visualization flag. When the flag is on, the method should keep track of each sampling step. The tracked sampling steps will be used to show the animated sampling algorithm.