Prepare for 1.0 release about rosu-memory

[486c]

Feel free to discuss & add something that you think should be present in 1.0 release

[S1n1st3rn3ss]

I think a slight change to json structure (and Values) are warranted as the current form of it is a bit too clunky:

• Move pp and sr to separate structs (because I plan on adding 100-95% acc pp calculation later on, as well as gradual sr calculation, and having many pp/sr values in main struct would be bad UX for overlay creation)
• @uzervlad wanted to get Bancho data to a usable state, and that would create some overlaps (specifically username, might be more than that)
• Similar issue might happen if we start storing pre- and post-mod map stats like AR/CS and BPM, so splitting song select stuff from gameplay data could be handy
• Implementing some struct methods could be nicer this way, especially in the longer run

I might be missing downsides but in general a slight refactor of Values seems like a nice thing to do (if we agree on what should go where)