Variyak

This crate provides a macro call_variadic which can be used to construct boilerplate code to call variadic functions using data from a container such as a Vec.

Example:

```rust

![feature(c_variadic)]

use variyak::call_variadic;

fn main() { let data = vec![1, 2]; let arg = 0;

#[no_mangle]
pub unsafe extern "C" fn my_func(_fixed: u32, mut _args: ...) -> bool {
    true
}

unsafe {
    assert!(call_variadic!(
        2,                  // maximum number of arguments to expand
        data,               // container identifier
        n,                  // index identifier
        data[n],            // argument expression: get `argument` at index `n`
        my_func(arg, ...)   // function to call, `...` is the variadic arguments
    ));

    assert!(call_variadic!(2, data, n, data[n], my_func(arg, arg, ..., arg)));
    assert!(call_variadic!(2, data, n, data[n], my_func(arg, ..., arg)));
    assert!(call_variadic!(2, data, n, data[n], my_func(arg, 42 + 27, ..., arg, 10usize)));
};

} ```