Allow for multiple trees

[SZanlongo]

Implement RRT incorporating an arbitrary number of trees besides trees growing from the start and goal. The tree structure already allows for multiple trees, but RRT must be modified to allow for extra trees.

[Sashank172001]

Could you please let me know what changes have to be made to the code to get multiple rrt paths

[SZanlongo]

This issue pertains to allowing multiple trees, not multiple paths. If you do in fact want multiple different paths, you could try simply running things multiple times, or perhaps skipping the pruning step and selecting multiple paths from the full tree. However, this would result in the paths being less direct that the pruned path.