Changed 'find_top_NOC_and_discipline' to for same number of athletes

Updated formatting to improve readability.

File introduced by doctests.

Updated code styling to comply with pep8 standards fully.

Updated doctests for main methods.

Fixed issue with not outputting correct number of names.

BREAKING CHANGE
Before this fix some names would be emitted from output.

Renamed file in order to comply with conventions.

Created test environment by importing doc test.

Added button in GUI to exit the application.

Updated commenting across parts of code.

Added decorator function to clean data imported by generator.

Changed import athlete list to generator function "import_data_by_row".

Changed commenting to comply with PEP8 line length standard.

Improved docstring and single line commenting across the program.

Moved data handling functions into class and GUI class inherits this.

Moved button creation into class initialisation.

Corrected spelling of "GraphicalUserInterace" to GraphicalUserInterface.

Changed order of class methods in GraphicalUserInterface.

Changed external functions to class methods.

Created a function to clear tkinter grid rather than reusing code twice.

Changed listbox function to include new parameter, reducing total code.

Created a new GUI method for the creation of buttons.

Remove line "import os" as os library went unused.

Remove bug in GUI which would leave the longest names on the screen.

Improve look of GUI by adding colours and changing button sizes.

Remove code designed for CLI outut which is redudant.

Introduce new GUI and remove old functions designed for CLI only.

Remove code for the FR2 function, as all functionalites included in FR3.

Make code more easily usable and output in console more aesthetically.

Improve FR3 commenting and remove redudant lines of code.

Add missing comments to  the split athlete list function.

Create a function to split a list of athletes: Name, NOC, Discipline.

Create function to list the top discipline for NOCs highlighted in FR2.

Change output for FR2 from 6 of the top NOCs to the correct 5.

Create function to list the top 5 NOCs by number of athletes.

Added more comments to to increase readability and flow of program.

Remove reduant line of code which shouldn't be present.

Update line length to comply with PEP8 79 character limit.

Create function to list shortest & longest names w/ NOC and discipline.

Updated project settings to reflect PEP8 , 79 characters per line.