Added new Algorithm to find middle element of Linked List (#1822)

* Added new Algorithm to find middle element of Linked List

* Rename MiddleElementOfLinkedList.py to middle_element_of_linked_list.py

* changed "middle_element_of_linked_list.py" algorithm for taking input

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Update middle_element_of_linked_list.py

* Whack the trailing whitespace

Co-authored-by: Christian Clauss <cclauss@me.com>