added:

1. ability to define "top" instead of "bottom".
2. ability to define id for a box.
3. ability to define "top" as the bottom of another box, using "top:{box:boxID}". can also add "offset" in the top object to space from bottom. good for:
	3.1. convenience. don't have to know exact location, just relative to other box.
	3.2 streams that are in boxes with no height have "dynamic" height per their content. this allows to place content below them without having to measure in advance