Resolve "Consider using the `genpdf` crate for generating PDF documents from analysis reports."

Closes #73 (closed)

examples/spectrum_test.rs

 use std::path::Path;
 
 use opossum::error::OpossumError;
+use opossum::plottable::Plottable;
 use opossum::spectrum::{create_visible_spectrum, Spectrum};
 use uom::si::{f64::Length, length::nanometer};
 
@@ -36,12 +37,12 @@ fn main() -> Result<(), OpossumError> {
         0.02,
     )?;
     s.sub(&s3);
-    s.to_plot(Path::new("spectrum.svg"));
+    s.to_svg_plot(Path::new("spectrum.svg"))?;
 
     let s4 = Spectrum::from_csv("NE03B.csv")?;
-    s4.to_plot(Path::new("ne03b_raw.svg"));
+    s4.to_svg_plot(Path::new("ne03b_raw.svg"))?;
     let mut s5 = create_visible_spectrum();
     s5.resample(&s4);
-    s5.to_plot(Path::new("ne03b.svg"));
+    s5.to_svg_plot(Path::new("ne03b.svg"))?;
     Ok(())
 }