Add 2D trimesh example.

examples2d/all_examples2.rs

@@ -21,6 +21,7 @@ mod platform2;
 mod pyramid2;
 mod restitution2;
 mod sensor2;
+mod trimesh2;
 
 fn demo_name_from_command_line() -> Option<String> {
     let mut args = std::env::args();
@@ -65,6 +66,7 @@ pub fn main() {
         ("Pyramid", pyramid2::init_world),
         ("Restitution", restitution2::init_world),
         ("Sensor", sensor2::init_world),
+        ("Trimesh", trimesh2::init_world),
         ("(Debug) box ball", debug_box_ball2::init_world),
     ];