clang-format

A basic clang-format Rust wrapper.

This allows for formatting a given input using clang-format from the system.

```rust use clangformat::{clangformat, ClangFormatStyle, CLANGFORMATSTYLE};

fn main() { CLANGFORMATSTYLE.set(ClangFormatStyle::Mozilla);

let input = r#"
    struct Test {

    };
"#;
let output = clang_format(input);
assert!(output.is_ok());
assert_eq!(output.unwrap(), "\nstruct Test\n{};\n");

} ```