Osu: Add setting to hide perfects(Greats) on osu!standard

[Joehuu]

I like the osu! new default skin. As skins become somewhat implemented, I would've made a 1x1 transparent png to hide the "Greats." It's a great opportunity to have a setting on this, so skinners won't need to make those transparent pngs. Like the same with slider ends, you completely removed it, I think. I play only this gamemode. Idk if this bothers other gamemodes.

[peppy]

This is planned for the skinning system.