v1.13.0

Added

• Masks. Any video, image, SVG, text or adjustment clip can carry a stack of
  masks (props.masks, up to 8): rectangle, ellipse, bezier (pen tool with
  curve handles) and free-hand (a drawn outline fitted into an editable
  bezier). Each has a mode (add, subtract, intersect, difference), invert,
  opacity, feather and expansion, and every shape parameter can be keyframed,
  bezier outlines included. Masks follow the clip's transform and render the
  same in preview and export. The Inspector's Masks section draws and edits
  them on the monitor and has a matte view.
• Agents: patch ops setMask, removeMask and setMaskKeys; props.masks
  is validated on addClip / updateClip; fablecut_scopes {mask:{clip}}
  reports how much of the clip its masks keep; the compact project view lists
  each clip's masks.
• Color layers' masks can be bezier or free-hand too (Draw in the Color
  tab, or shape:"bezier" / "freehand" in setGradeLayer).
• Track mattes. A clip can be cut by the picture on another track (the
  video track above by default): props.matte = alpha, alpha-inverted,
  luma or luma-inverted, props.matteTrack to pick the track. The matte
  track stops drawing while it is in use; the timeline marks both sides. In the
  Inspector under Blend; agents use the setMatte patch op, and
  fablecut_scopes lists each clip's matte and blend.
• Motion tracking. Follow a point or a region of a video clip frame by
  frame (template matching, sub-pixel, optionally with scale and rotation);
  the track is stored on the clip (props.tracks). A mask's ◀ Back / On ▶
  buttons track what it covers and key its position (and scale / rotation);
  the Inspector's Tracking section tracks points and attaches any
  visual clip to a track as editable keyframes. Esc stops a running track.
• Agents: the fablecut_track tool (track a point, a region or a mask, then
  apply it to a mask or a clip) and the removeTrack patch op; tracks are
  validated on addClip / updateClip and summarized in the compact view.
• Blend modes: color-burn, exclusion, hue, saturation, color and
  luminosity join the list (17 in all). blend, matte and matteTrack are
  validated on addClip / updateClip.