Add Child Generator Deque Search algorithm

[ed741]

Adds the 'Child Generator Deque Search' algorithm to PathBench. Based on algorithm in: https://arxiv.org/abs/2101.08715

In each iteration of the algorithm the front of a deque is polled for a node (coordinate, cost, parent node, child-generator):

• If the node hasn't been visited before:
  • The node is checked to see if it is at the goal position, if so return the path.
  • If the node has the lowest cost so far for its position record the cost and parent node into maps: coordinate -> cost, and coordinate -> previous-coordinate
  • A 'generator function' (implemented as a list for simplicity) is produced that produces gets the child nodes from this current node. The child generator function produces the child nodes ordered by closest euclidean distance to goal
• If the child-generator it is empty skip to the next iteration.
• The child-generator is polled, put the child node at the front of the deque (child-coordinates, cost+movement, current node, None) and the parent node (along with child generator function) at the back.

[judicaelclair]

@ed741 please rebase your branch so that tests can be re-run with the metaclass conflict fix.

[ed741]

Hi, I've rebased it but i'm not sure how the errors are related to my code. Seems like some image file reading problem?

[judicaelclair]

Ah yes, the tests have mood swings.... I'll fix it.

[judicaelclair]

@ed741 @uncobruce @husseinalijaafar the reason why the tests were failing was due to the algorithm ordering. Putting the new one before RRT meant the RRT algorithms were to far down the drop-down list in the GUI, which made them drop off screen. Keep that in mind in the future when you try to add new algorithms. I've fixed it for this one directly on the master branch.

[uncobruce]

@judicaelclair Got it, thanks for your help again

[ed741]

Thank you for sorting it out :)