[FIRST] Plotly class approach
[ADD ] URL property
[ADD] XData YData extraction
[ADD] new scatter plot support
[ADD] plotly_figure as a subclass of the handle class
[FIX] histogram 2D bug
[ADD] more comments
[ADD] roadmap of parameters to set as comments
[FIX] marker color assignment if cell
[FIX] color handling for color property = 'none' / 'auto'
[UPDATE] graph reference
Merge branch 'fig2plotly2.0'
[DELETE] old test files and old Plotly class files