v0.17.0
- Add GR dependency to make it the default backend
- Improve histogram2d bin estimation
- Allow vector arguments for certain series attributes and support line_z and fill_z on GR, PyPlot, Plotly(JS) and PGFPlots
- Automatic scientific notation for tick labels
- Allow to set the theme in PLOTS_DEFAULTS
- Implement plots_heatmap seriestype providing a Plots recipe for heatmaps