dunnart: rename some types

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
dunnart: modify examples to exercise code better

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
dunnart:modify parse to use moveFront() and move try out of main loop

I.e. put the main loop inside the try statement

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>