Add support for SuperCollider code TODO scanning

The [SuperCollider](https://supercollider.github.io/) programming language uses C-style `//` single line comments and `/* */` block comments, with the only possible wrinkle being that it allows block comment nesting, meaning the expression:

```
/* Outer block
  /* Inner block */
 */ 
```

Is valid SuperCollider code. SuperCollider uses the `.sc` and `.scd` file extensions.