Macro fixt::fixt

macro_rules! fixt {
    ($name : tt) => { ... };
    ($name : tt, $curve : expr) => { ... };
    ($name : tt, $curve : expr, $index : expr) => { ... };
}

tiny convenience macro to make it easy to get the first Foo from its fixturator without using the iterator interface to save a little typing c.f. fixt!(Foo) vs. FooFixturator::new(Unpredictable).next().unwrap();