Confusing IDs in the download part of plot-with-settings

[pawelru]

In addition to #241

I have found confusing the approach of giving the IDs to the elements. Please find a few examples below:

• #plot_with_settings-downbutton-downl

  • Why to put "download" twice?
  • Why two distinct shortcuts for the "download" - here: "down" and "downl".
  • Why to put the class "button" in the element ID?

• #plot_with_settings-downbutton-data_download

  • (all of above)
  • it downloads the plot and it has nothing with the data