As a programmer, I want to create function names with arbitrary characters. so that I can overload operators

See [request on Hacker News](https://news.ycombinator.com/item?id=8018113)

One possibility would be to allow arbitrary characters in function definitions and invocations, though that might lead to ambiguities in the grammar.

``` go
func **(x, y) {
    Math::pow(x, y)
}

test.fact("Can use operators",

    2 ** 3,  =>, 8.0,
    10 ** 2, =>, 100.0
)
```
