list bundle changes
- removed alternate toString() method. It was more or less
just getFormat().toString()
- removed createList method, and added another constructor instead
to be more line with the rest of the classes's extensibility
- couple clarity changes: skip -> SKIP as per it being a constant,
don't cover for some kind of crazy rogue bundle field impl that lets
fields have no index, explicit init for peek etc
- most importantly fix bundle interator to not mishandle fields past
its scope size. ie fields in the format that it does possess but have
an index higher than its internal list size