v0.3.0

Added

plt

• SubplotBuilder and Plotter for builder pattern subplot and plot construction.
• builder function to Subplot for getting a builder.
• Default constructor for Figure.
• Layouts for setting subplot areas
• visible member of SubplotDescriptor to control the visibility of an axis line.
• grid example.

Changed

plt

• Moved from an init struct pattern, to builder pattern for constructing plots and subplots.
• Changed FigureDescriptor to FigureFormat.
• Changed name of pretty example to detailed.
• Split Ticker into separate TickSpacing and TickLabels structs.
• Auto varients of TickSpacing and TickLabels now determine if they should exist
  based on whether a plot uses that axis.
• Updated examples.

plt-draw

• Changed GraphicsType to ImageType.

Removed

plt

• SubplotDescriptor, Axis, and PlotDescriptor from public API.
• Removed Figure::add_subplot in favor of using layouts.