All nodes in one place when no bounds are defined

[CoderAllan]

When no bounds tag is specified in the nodes then all Examples of the behavior:

• https://github.com/clovett/dgml/blob/master/demos/ConditionalStyles/linesofcode.dgml
• https://github.com/clovett/dgml/blob/master/demos/ConditionalStyles/callsequence.dgml

The correct behavior should be to use the Cose layout if no nodes have that 'bounds' tag defined.