Allow Default::default() pattern

[sezna]

One pattern I use a lot in Rust is Default::default() to construct a default instance of a type. However, pedantic clippy settings state that this is unclear. I personally dislike this setting, and actually find Default::default() more usable and consistent.

Consistency wise, there's no reason (IMO) for clippy to single out the Default trait. We access other trait methods in this way, and clippy has no such rule against other traits. For example, Into::into(), or Display::to_string().

Style wise -- the point of using a language with type inference is that you only have to specify the type once, and then subsequent lines of code do not need to redeclare (or "stutter") the type. I will frequently update an underlying data structure, e.g. switching from HashMap to BTreeMap, or Vec to HashSet. If I've used Default::default() everywhere, I do not need to go update those invocations. However, if I've followed clippy's advice, I have a lot more refactoring to do -- I have to go call HashMap::default() or whatever everywhere.

These are just some examples to prove a point -- in my opinion, this pattern is clear, idiomatic, and consistent.

[DmitryVasilevsky]

I agree with Clippy here, but since most people disagree, I'll just have to live with it.