rbKarel play sounds

```
Add a KarelSounds folder to the list of folders for which is searched.

If present, it should contain sounds which will be named after the filename,
with any extensions
removed.

These can be played in the script using the sound name in quotes.

eg: if there is a sound file scream.wav then the rbKarel syntax would be:
play "scream"
or
playLoop "scream"
```

Original issue reported on code.google.com by `dentaroo@gmail.com` on 30 Apr 2009 at 9:10