Many small fixes

- Flip writing order of effect colour blocks every other block write to try
  and even out. Previously the bottom rows were always last to be written.
- Add more examples: ball, comet, pulser.
- Refine the keyboard layout grid for GX502.
- Use tokio to delay main loop, not thread::sleep
- Minor tweaks to error handling. Needs refactor of errors.

rog-core/src/config.rs

@@ -31,6 +31,7 @@ impl Config {
                 let mut c = Config::default();
                 c.current_mode[0] = 0x5d;
                 c.current_mode[1] = 0xb3;
+                // Should be okay to unwrap this as is since it is a Default
                 let toml = toml::to_string(&c).unwrap();
                 file.write_all(toml.as_bytes())
                     .expect("Writing default config failed");