Add score column by calculating freq*length.

[xslendix]

Closes #36.

[Raymo111]

Let's implement score into the CLI words command and csv export as well.

Notes for this:

• Sort by score by default in all cases where that makes sense (i.e. basically what was frequency before, but double check).
• Consider updating the word structure in Definitions.py to include a score attr, if it makes sense to, to avoid repetition of code
• Extract the score calculation into a separate function for decoupling/future maintainability

[Raymo111]

Almost there, GUI needs to sort by score desc and not word desc, that's the last issue