misc: create indexes for common fields to improve query performance

[TrueRou]

Its a problem that bancho.py doesn't originally create indexes for common fields like map_md5 and userid in scores table, filename in maps table, for example.
It's significant for a medium or large server to query with a indexed table.

[cmyui]

Yeah, I've been wanting to do this for a while - pretty high priority I'd say.

Tricky to find enough data to accurately test it with - ideally I'd like to do it with Akatsuki's full database, but we don't have an updated migration script..

[cmyui]

@xxCherry by any chance, happen to have that old akatsuki->bancho.py migration script lying around anywhere?

[tsunyoku]

@xxCherry by any chance, happen to have that old akatsuki->bancho.py migration script lying around anywhere?

hey we wrote one remember :P
no clue where it is, but we made one