- add increment/decrement, repositioning. Simplify const_iterator.
- this makes is much easier to use labelRange for constructing ranges of
sub-lists. For symmetry with setSize() it has a setStart() instead of
simply assigning to start() directly. This would also provide the
future possibility to imbue the labelRange with a particular policy
(eg, no negative starts, max size etc) and ensure that they are
enforced.
A simple use case:
// initialize each to zero...
List<labelRange> subListRanges = ...;
// scan and categorize
if (condition)
subListRanges[categoryI]++; // increment size for that category
// finally, set the starting points
start = 0;
for (labelRange& range : subListRanges)
{
range.setStart(start);
start += range.size();
}