exec: A Rust library to replace the running program with another

This is a simple Rust wrapper around execvp. It can be used as follows:

```rust // Get our command line args, dropping the first one. let args: Vec = env::args().skip(1).collect(); let program = args[0].clone();

// Exec the specified program. Note that we pass args[0] twice: Once as // the name of the program to execute, and once as the first argument. // // If all goes well, this will never return. If it does return, it will // always retun an error. let err = exec::execvp(program, &args); println!("Error: {}", err); ```