DoodleBUGS: Allow overlapping plates

[shravanngoswamii]

Well, Cytoscape does not support overlapped compound nodes, it seems like cytoscape communtiy don't have any plans to include it, see cytoscape/cytoscape.js#2220, it clearly says

Compound nodes are not intended to be used for overlapping sets: Compounds exist in a strict tree hierarchy. That can not change in the model.

We can try to use bubblesets for grouping something for this case, see https://github.com/upsetjs/cytoscape.js-bubblesets (for more understanding of bubblesets, see these:

• https://ieeexplore.ieee.org/document/5290706
• https://www-ui.is.s.u-tokyo.ac.jp/~takeo/papers/watanabe_uist2007_bubble.pdf