Improvements to the main project and the GUI

[RatserX]

Here's a couple of improvements I did, mostly to the GUI:

• Project:
  • Add a .gitignore file to avoid pushing certain Python related files and folders, this includes the config.json file too.
  • Add a requirements.txt file to easily install all related dependencies (updated the README file to mention this).
• GUI:
  • Avoid O(n*2) loop when processing player info.
  • Sort player names in alphabetical order.
  • Set fixed window size to 350x250.
  • Disable option to resize window.
  • Increase width of comboboxes so that all names fit correctly.
  • Fix external save files showing as blank in the comboboxes, showing the filename GUID instead.
  • Add spacing between group of elements.

Here's how the GUI window currently looks like with these changes: