Derive FromIterator

[benediktsatalia]

I was a bit surprised that there is no derive in this crate for FromIterator. There is one for IntoIterator so I feel FromIterator is the natural dual from that.

Maybe the reason is that it would not be clear what the generic parameter of FromIterator would be for the derive, but I thought it could be fully generic, and could expand to something like:

impl <GenericsOfStruct, T>  FromIterator<T> for Struct<GenericsOfStruct>
where
     InnerStruct<GenericsOfInnerStruct>: FromIterator<T>
{
     ...
}