v0.1.5 — Guava

Added

• X and Y axis labels via Config::x_axis_label() and Config::y_axis_label().
  The Y-axis label renders flush left above the graph body. The X-axis label
  renders inline on the same row as the axis line, to the right of the tick
  marks. The X-axis label only appears when x_axis_range is also configured.

• Added examples/axis_labels.rs demonstrating both labels on a 20-point
  dataset with a configured X-axis range.

• Serde support via an optional serde feature flag. Add
  asciigraph = { version = "0.1.5", features = ["serde"] } to enable
  Serialize and Deserialize for Config, AnsiColor, CharSet,
  ZeroLine, and Threshold. Formatter closure fields are skipped during
  serialization as functions cannot be represented as data.

• Added examples/serde_config.rs demonstrating serialization and
  deserialization of Config to and from JSON using serde_json.

• Statistical annotations via StatAnnotations — opt-in horizontal reference
  lines computed automatically from the data and rendered with inline labels.
  Supports minimum, maximum, mean, median, and standard deviation (rendered
  as two lines at ±σ). Each annotation uses a distinct dashed character for
  visual clarity. When two annotation values map to the same grid row, their
  labels are stacked and separated by a comma. In multi-series graphs, the
  target series is configurable via series_index. Enabled through
  Config::stat_annotations().

• Added examples/stat_annotations.rs demonstrating all five annotations
  rendered in yellow over a 20-point dataset.

Changed

• Threshold now supports series_index — each threshold is associated
  with a specific series and two rules are applied before rendering. The
  visibility rule skips a threshold if its value falls outside the min/max
  range of its associated series specifically, not just the global graph
  range. The color inheritance rule automatically applies the associated
  series' color to the threshold line when no explicit color is set, creating
  a natural visual association between a threshold and its series. Both rules
  default gracefully — series_index defaults to 0 and an explicit color
  always takes priority over the inherited series color.

• Updated examples/threshold.rs to demonstrate both single-series and
  multi-series threshold usage, including the visibility rule and color
  inheritance rule.

• Refactored options.rs into a module directory (src/options/) with three
  focused files, mirroring the structure used by src/asciigraph/:

  • charset.rs — CharSet, DEFAULT_CHAR_SET, and create_char_set
  • config.rs — Config struct and all its builder methods
  • extensions.rs — ZeroLine, Threshold, and StatAnnotations

  No public API changes — all types remain accessible at the same paths as before.