Graphics namespace includes rectangle, rounded rectangle, and circle

Also added methods to make writing to shm pool easier

src/main.rs

@@ -3,6 +3,7 @@ use std::error::Error;
 
 mod wayland;
 use wayland::wl_client::WlClient;
+mod graphics;
 
 fn main() -> Result<(), Box<dyn Error>> {
     let mut wl_client = WlClient::new()?;