Add very simple "to_dot" function to opticscenery

src/lib.rs

+//! This is the documentation for the OPOSSUM software package. OPOSSUM stands for OPen-source Optics Simulation Software and Unified Modeller.
+//! 
+/// The basic structure containing the entire optical model
 pub mod opticscenery;
\ No newline at end of file

src/opticscenery.rs

 use petgraph::prelude::DiGraph;
+use petgraph::dot::Dot;
 
 #[derive(Default, Debug)]
 pub struct Opticscenery {
   g: DiGraph<i32,()>
+}
+
+impl Opticscenery {
+  pub fn to_dot(self: &Self) -> String {
+    format!("{:?}",Dot::new(&self.g))
+  }
 }
\ No newline at end of file