Reorganize the shared example code

The new layout deviates from what the Rust book suggests

  https://doc.rust-lang.org/book/ch11-03-test-organization.html#submodules-in-integration-tests

and uses the frowned-upon `#[path]` attribute,

  https://doc.rust-lang.org/style-guide/advice.html#modules

but we've decided that having a descriptive module filename instead of
`mod.rs` is worth the cost.

app-proto/examples/common/print.rs

@@ -4,11 +4,11 @@ use nalgebra::DMatrix;
 
 use dyna3::engine::{Q, DescentHistory, RealizationResult};
 
-pub fn print_title(title: &str) {
+pub fn title(title: &str) {
     println!("─── {title} ───");
 }
 
-pub fn print_realization_diagnostics(realization_result: &RealizationResult) {
+pub fn realization_diagnostics(realization_result: &RealizationResult) {
     let RealizationResult { result, history } = realization_result;
     println!();
     if let Err(ref message) = result {
@@ -20,15 +20,15 @@ pub fn print_realization_diagnostics(realization_result: &RealizationResult) {
     println!("Loss: {}", history.scaled_loss.last().unwrap());
 }
 
-pub fn print_gram_matrix(config: &DMatrix<f64>) {
+pub fn gram_matrix(config: &DMatrix<f64>) {
     println!("\nCompleted Gram matrix:{}", (config.tr_mul(&*Q) * config).to_string().trim_end());
 }
 
-pub fn print_config(config: &DMatrix<f64>) {
+pub fn config(config: &DMatrix<f64>) {
     println!("\nConfiguration:{}", config.to_string().trim_end());
 }
 
-pub fn print_loss_history(history: &DescentHistory) {
+pub fn loss_history(history: &DescentHistory) {
     println!("\nStep │ Loss\n─────┼────────────────────────────────");
     for (step, scaled_loss) in history.scaled_loss.iter().enumerate() {
         println!("{:<4} │ {}", step, scaled_loss);

app-proto/examples/irisawa-hexlet.rs

@@ -1,18 +1,13 @@
-mod common;
+#[path = "common/print.rs"]
+mod print;
 
-use common::{
-    print_gram_matrix,
-    print_loss_history,
-    print_realization_diagnostics,
-    print_title
-};
 use dyna3::engine::{Realization, examples::realize_irisawa_hexlet};
 
 fn main() {
     const SCALED_TOL: f64 = 1.0e-12;
     let realization_result = realize_irisawa_hexlet(SCALED_TOL);
-    print_title("Irisawa hexlet");
-    print_realization_diagnostics(&realization_result);
+    print::title("Irisawa hexlet");
+    print::realization_diagnostics(&realization_result);
     if let Ok(Realization { config, .. }) = realization_result.result {
         // print the diameters of the chain spheres
         println!("\nChain diameters:");
@@ -22,7 +17,7 @@ fn main() {
         }
         
         // print the completed Gram matrix
-        print_gram_matrix(&config);
+        print::gram_matrix(&config);
     }
-    print_loss_history(&realization_result.history);
+    print::loss_history(&realization_result.history);
 }

app-proto/examples/kaleidocycle.rs

@@ -1,24 +1,19 @@
-mod common;
+#[path = "common/print.rs"]
+mod print;
 
 use nalgebra::{DMatrix, DVector};
 
-use common::{
-    print_config,
-    print_gram_matrix,
-    print_realization_diagnostics,
-    print_title
-};
 use dyna3::engine::{Realization, examples::realize_kaleidocycle};
 
 fn main() {
     const SCALED_TOL: f64 = 1.0e-12;
     let realization_result = realize_kaleidocycle(SCALED_TOL);
-    print_title("Kaleidocycle");
-    print_realization_diagnostics(&realization_result);
+    print::title("Kaleidocycle");
+    print::realization_diagnostics(&realization_result);
     if let Ok(Realization { config, tangent }) = realization_result.result {
         // print the completed Gram matrix and the realized configuration
-        print_gram_matrix(&config);
-        print_config(&config);
+        print::gram_matrix(&config);
+        print::config(&config);
         
         // find the kaleidocycle's twist motion by projecting onto the tangent
         // space

app-proto/examples/point-on-sphere.rs

@@ -1,12 +1,6 @@
-mod common;
+#[path = "common/print.rs"]
+mod print;
 
-use common::{
-    print_config,
-    print_gram_matrix,
-    print_loss_history,
-    print_realization_diagnostics,
-    print_title
-};
 use dyna3::engine::{
     point,
     realize_gram,
@@ -29,11 +23,11 @@ fn main() {
     let realization_result = realize_gram(
         &problem, 1.0e-12, 0.5, 0.9, 1.1, 200, 110
     );
-    print_title("Point on a sphere");
-    print_realization_diagnostics(&realization_result);
+    print::title("Point on a sphere");
+    print::realization_diagnostics(&realization_result);
     if let Ok(Realization{ config, .. }) = realization_result.result {
-        print_gram_matrix(&config);
-        print_config(&config);
+        print::gram_matrix(&config);
+        print::config(&config);
     }
-    print_loss_history(&realization_result.history);
+    print::loss_history(&realization_result.history);
 }

app-proto/examples/three-spheres.rs

@@ -1,11 +1,6 @@
-mod common;
+#[path = "common/print.rs"]
+mod print;
 
-use common::{
-    print_gram_matrix,
-    print_loss_history,
-    print_realization_diagnostics,
-    print_title
-};
 use dyna3::engine::{realize_gram, sphere, ConstraintProblem, Realization};
 
 fn main() {
@@ -25,10 +20,10 @@ fn main() {
     let realization_result = realize_gram(
         &problem, 1.0e-12, 0.5, 0.9, 1.1, 200, 110
     );
-    print_title("Three spheres");
-    print_realization_diagnostics(&realization_result);
+    print::title("Three spheres");
+    print::realization_diagnostics(&realization_result);
     if let Ok(Realization{ config, .. }) = realization_result.result {
-        print_gram_matrix(&config);
+        print::gram_matrix(&config);
     }
-    print_loss_history(&realization_result.history);
+    print::loss_history(&realization_result.history);
 }