LrmScale: add get_measure and get_position to work on scale positions

Author: Tristramg

src/lrm_scale.rs

@@ -423,17 +423,20 @@ pub mod tests {
 
     #[test]
     fn get_measure() {
+        // a(scale 0)----measure(scale 5)----b(scale 10)
         let measure = scale().get_measure(5.).unwrap();
         assert_eq!(measure.anchor_name, "a");
         assert_eq!(measure.scale_offset, 5.);
 
+        // a(scale 0)----b(scale 10)----measure(scale 25)
         let measure = scale().get_measure(25.).unwrap();
         assert_eq!(measure.anchor_name, "b");
         assert_eq!(measure.scale_offset, 15.);
     }
 
     #[test]
     fn get_position() {
+        // a(scale 0)----position(scale a+5)----b(scale 10)
         let position = scale()
             .get_position(LrmScaleMeasure {
                 anchor_name: "a".to_string(),
@@ -442,6 +445,7 @@ pub mod tests {
             .unwrap();
         assert_eq!(position, 5.);
 
+        // a(scale 0)----b(scale 10)----position(scale b+15)
         let position = scale()
             .get_position(LrmScaleMeasure {
                 anchor_name: "b".to_string(),