Motivation: TB should give ability to save line chart as high quality
SVG.
Right solution: Modify Plottable to draw in one SVG with grouping
instead of multiple SVG fragments.
Problem: SVG creation is scattered and it may require a lot more effort
to understand design choice around these fragments (may require dynamic
creation of clipPath for masking a part of a figure)
Current solution: Parse the Plottable drawn DOM and generate one SVG out
of the DOM snapshot
Shortcomings:
- X-axis label may take up larger than required space
- There are no labels to each line (should give an option when
  exporting)