Difficulty based ordering field fix

[LatidoReMe]

• When ordering by a difficulty's difficulty, will see an image to the left & the numbers represented as the note images!
• Same goes for a difficulty's notes! However, listview will lack the notes suffix
• Songs don't require the difficulty to display notes anymore, and vice versa! That means no more None notes, and no more accidental item breaks by one accidental input (hopefully) close #132

[db0company]

Good stuff 👍