update plotlines in animations
add plotline for first serie in scatter.js
add plotlines to scatter_animation json schema
refactor plotlines update
add initial plotlines using chart.addPlotLine
use App.add_plotLines for update
use chart_type to compute the plotlines
pass chart_type as parameter when updating plotlines
add plotlines to  scatter post-rendering
add plotlines(if specified in schema) to columns.js
fix add_plotLines for single plotline case
fix plotlines update for columns
fix plotlines update for non multiseries
fix bubbles plotlines
add plotlines to schema
Merge branch 'fix-plotlines'