Added convert_sequence() to the CLI

Created a new argument -S (sequence), off by default
Added default settings handlers (different default settings depending on the conversion mode)
The full list of settings, including defaults, is now displayed when the script is run
The info output is divided into blocks (settings, input, output)
Changed the way the script predicts time (higher accuracy for different conversion modes)
Some linter fixes (naming style, indentation, docstrings etc)
Updated README.md

sedthh / pyxelate