Remove unnecessary initial goal test in best_first_graph_search. The loop will catch that case immediately.

To make it more accurate.

To make it more descriptive and accurate.

* added relu activation

* added default parameters

Added a few new sentences, modified the sentence structure at a few places, and corrected some grammatical errors.

`self.heap.append` simply appends to the end of the `self.heap` 
Since `self.heap` is just a python list. 
`self.append` calls the append method of the class instance, effectively putting the item in its proper place.

A thank you to contributors from the GSoC 2018 program!

* Revamped the notebook

* A few changes reversed

Changed a few things from my original PR after a review from ad71.

Made a colored table to display dog movement instead. Corrected grammatical errors, improved the sentence structure and corrected any typos found.

Typos and minor other text errors removed

Corrected typos + minor other text changes

Shortened it, finding conflicts separately and storing them in different variables has no use later in the notebook; so i believe this looks better.