Make SequenceNode final

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Printing and error reporting should be on the slow path

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added toString() for debugging

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Made code a little more concise, and the loop count reporting should only be done in interpreter anyway, so it's on the slow path (I assume)

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Be more specific with the type

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Quick and dirty addition of executeVoid, try to cut off side-effect free operations as early as possible

The many executeVoid NOOP methods could be reduced by some classes for side-effect-free expressions

Signed-off-by: Stefan Marr <git@stefan-marr.de>