[kvdb-memorydb] Migrated code to 2018 edition, updated parking_lot

[expenses]

See #143.

[parity-cla-bot]

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Many thanks,

Parity Technologies CLA Bot

[dvdplm]

lgtm but I'm a bit worried about the parking_lot update.

[dvdplm]

We're on 0.8 in parity-ethereum and I have a hunch that this could break things. If you feel like trying this change against the master branch over there, that'd be fantastic.

[expenses]

There are some breakages such as

error[E0277]: the trait bound `kvdb_memorydb::InMemory: kvdb::KeyValueDB` is not satisfied
   --> miner/local-store/src/lib.rs:219:30
    |
219 |             let store = super::create(db.clone(), None, Dummy(vec![]));
    |                                       ^^^^^^^^^^ the trait `kvdb::KeyValueDB` is not implemented for `kvdb_memorydb::InMemory`
    |
    = note: required for the cast to the object type `dyn kvdb::KeyValueDB`

Perhaps this should be version 0.2.0?

[dvdplm]

@expenses you mean change this crate to v0.2.0? If we upgrade parking_lot to a breaking version then yes.
I haven’t looked closely at the error you posted yet but it could be we need to update all of parity-ethereum at once, or is that what you did perhaps?

The best way imo would be to revert the parking_lot upgrade and get this merged, then we deal with upgrading the reps separately.

And thanks again for your work here! :)

[expenses]

Sure, I'll do that.