add insertChild method in SequenceNodeIF

[Stephen Siegel]

I would find it very convenient to add a method to SequenceNodeIF

void insertChild(int position, T child);

which inserts a child node at position, shifting the node that was at position to position+1, etc.

[Stephen Siegel]

In case it helps (probably not), here is how I was trying to do it:

	private void insertNode(int position, SequenceNodeIF<GlobalScopeNodeIF> sequence,
			GlobalScopeNodeIF newNode) {
		int numChildren = sequence.numChildren();
		GlobalScopeNodeIF previous = newNode;

		while (position < numChildren) {
			GlobalScopeNodeIF current = (GlobalScopeNodeIF) sequence.child(position);

			sequence.setChild(position, previous);
			previous = current;
			position++;
		}
		sequence.setChild(position, previous);
	}