Rust bindings for RV

Safe bindings for the RV.

Example

use rsrv::rv::*;

fn main() {
    let cpu = RV::new(0x10000, vec![0x02A88893, 0x00000073]);

    while RV::step(cpu) != RV_EECALL {}

    println!(
        "Environment call @ {:08x}: {}",
        RV::get_pc(cpu),
        RV::get_r(cpu)[17]
    );
}