How to handle figure with multiple charts

[elonzh]

For example:

(a) chart a (b) chart b
Fig 1. figure caption

and the callouts in body are Fig 1(a), Fig 1(b)

[kermitt2]

Hi @elonzh !

I have planed to work on this in #963, identifying sub-parts in the a figure (by improving SVG/bitmap clustering) and sub-labels, but not sure about the result to be honest.