chartlet 0.6.0

Small panels, continued, and semibold text in PNG output. The specification keeps
schemaVersion: 1; every specification that rendered with 0.5.0 still renders, with the
changes in output listed under Changed and Fixed.

Added

• Time charts: timeAxis.min and timeAxis.max extend the time axis to a position such as a
  round year before the first observation.
• Time charts: "stroke": "medium", a two-pixel line for small panels.

Changed

• A compact time chart (below 320 pixels) makes its value-axis gutter as wide as its widest
  tick label needs.
• A time chart with neither a drawn title, a legend nor a value axis title above its first pane
  starts its plot near the top instead of keeping the title's room free.

Fixed

• PNG output draws semibold text semibold: the bundled semibold faces join the Inter family, so
  titles, axis titles, values and emphasized notes no longer fall back to the regular weight.