Added comments to main.py and removed hardcoded values from display.py to globals.py

[hlai1]

Changes

• added comments to main.py to increase readability
• removed the hardcoded values from display.py (numBars, delay, time_taken, etc.) and moved them to globals.py
• imported hardcoded values from globals.py to display.py for usage

Why (resolves #176)

• Increases readability of code
• Makes code cleaner and more module
• Global definitions are easier to reuse across multiple modules

How

• Went through main.py to understand logic, then commented the file
• Created globals.py file, moved the hardcoded values from display.py over
• Imported the values from globals.py into display.py for usage throughout the file

Testing

• Ran the data visualizer again, confirmed that functionalities still operated the same as before (timer, switching sorting types, etc.)

[idomeisner]

I don't think start_time and time_taken need to be globals.
They are relevant only for DisplayBox, why not add them as class or instance variables?
There are several options for how to implement this.
For example, you can set start_time when starting a new sort and update time_taken when calling the update method.
You can also save only start_time and directly do something like:
self.text = str(time() - start_time)[:6] + ' seconds'

[idomeisner]

I'm not sure sure DisplayBox is a good name, all boxes display something.
Looking at the other names TextBox, SlideBox, DropdownBox, ...
Maybe TimeBox or something like that would be better.