Adding unit tests for sorting functions, and improving readability on some sorting algorithms (#784)

* Adding variable to fade out ambiguity

* More readability on merge sorting algorithm

* Updating merge_sort_fastest description and explaining why

* Adding tests file with imports

* Standardazing filenames and function names

* Adding test cases and test functions

* Adding test loop

* Putting 'user oriented code' inside main condition for having valid imports

* Fixing condition

* Updating tests: adding cases and todo list

* Refactoring first euler problem's first solution

sorts/tree_sort.py

@@ -30,7 +30,7 @@ def inorder(root, res):
         res.append(root.val)
         inorder(root.right,res)
 
-def treesort(arr):
+def tree_sort(arr):
     # Build BST
     if len(arr) == 0:
         return arr
@@ -42,4 +42,5 @@ def treesort(arr):
     inorder(root,res)
     return res
 
-print(treesort([10,1,3,2,9,14,13]))
+if __name__ == '__main__':
+    print(tree_sort([10,1,3,2,9,14,13]))