Auto-size bubbles

[zepheiryan]

At least the scatter plot Flot view and its predecessor use the 'bubble' mechanism to generate fixed-size bubbles to show an item in a lens, by default 400x300px. This should be replaced by a mechanism that can autosize by at least the content width by default, unless specific dimensions are provided.

Height should probably be interpreted as a maximum suggestion; that is, the content is never forced to be longer and display as less than the given height but will resort scrollbars within the bubble if it exceeds the given specification.