v0.12.1

Added

• Add TypesScript definition, automatically generated from JSDoc comments
  (#1612).
• Support new Raster(size) constructor.
• Expose Raster#context accessor.
• Implement Raster#clear() method to clear associated canvas context.
• Node.js: Add support for Node.js v11 and v12.

Fixed

• Fix parsing of CSS colors with spaces in parentheses (#1629).
• Improve Color.random() documentation.
• Fix Tween#then() documentation.

Removed

• Node.js: Remove support for Node.js v6.