Separate big modules into smaller submodules

[clarity0]

Files are too long maybe, what do you think?

[evoxmusic]

That's good idea - but maybe it is too soon? What structure would you suggest?

[clarity0]

Something like this?

src
|--------protocol
|   |--------mod.rs
|   |--------error
|       |--------mod.rs
|       |--------redis_error.rs
|       |--------command_error.rs
|--------command
|   |--------mod.rs
|   |--------util.rs
|--------server
    |--------mod.rs
    |--------util
        |--------mod.rs
        |--------each util function
        |--------here in its own file

[evoxmusic]

It looks good for me - being consistent is the most important at our stage. What do you think @pjeziorowski?

Note to consider: I am working on a branch where I have modified a bit the structure as well. Maybe we are better to change all of that once I merged it into the main one?

The branch is to support the "cluster mode"

[pjeziorowski]

The structure LGTM.