use thread estimation if threads is set to 0

src/runner.rs

@@ -12,11 +12,18 @@ pub struct Runner {
 
 impl Runner {
     pub fn new(iterations: usize, threads: usize) -> Self {
-        Self {
+        if threads == 0 {
+            match std::thread::available_parallelism() {
+                Ok(threads) => Runner { iterations, threads: threads.get() },
+                Err(_) => Runner { iterations, threads: 1 },
+            }
+        } else {
+            Runner {
                 iterations,
                 threads,
             }
         }
+    }
 
     pub fn layout(self: &Self, number_of_nodes: usize, edge_list: Vec<(u32, u32)>) -> Vec<(f32, f32)> {
         // let edges = connection_matrix(size);