Get rid of clippy remainings.

[tomusdrw]

We don't really use this feature any more.

I tried running clippy as cargo plugin, but unfortunatelly it failed to compile Parity on latest nightly.

[svyatonik]

Does this also counts as 'clippy remainings'? :)
https://github.com/paritytech/parity/blob/master/parity/helpers.rs#L220
https://github.com/paritytech/parity/blob/master/parity/helpers.rs#L456
https://github.com/paritytech/parity/blob/master/util/patricia_trie/src/triedbmut.rs#L439

Maybe worth adding to this PR as well. Otherwise - lgtm.

[tomusdrw]

Good catch. Forgot to update sed params for those :)

[debris]

if we want to run clippy as a plugin, we should not remove those, but only rename to:

#[cfg_attr(feature="cargo-clippy", allow(needless_range_loop))]

[tomusdrw]

I tried running cargo-clipp as a plugin but it didn't work (I think parity failed to compile on nightly). Let's look at this from a fresh perspective when it works, some of the things here might not be valid any more, I would prefer to fix the code at some point rather than disable lints.
What do you think?

[debris]

fair enough ;)