tuple-fn

This crate provides [TupleFnOnce], [TupleFnMut] and [TupleFn], corresponding to [FnOnce], [FnMut] and [Fn].

[TupleFnOnce], [TupleFnMut] and [TupleFn] enables functions or closures to be called with a tuple of arguments. For example:

```rust use tuple_fn::*;

fn add(a: i32, b: i32) -> i32 { a + b }

let sum = add.callwithargstuple((1, 2)); asserteq!(sum, 3); ```

These three traits should be named as FnOnceCallWithArgsTupleExt, FnMutCallWithArgsTupleExt, FnCallWithArgsTupleExt by convention, because they are implemented for all corresponding FnOnce, FnMut, Fn types and act like extension traits. They are named as TupleFn* just for simplicity.