v2.5.0

Changes:

• Add tooltip support for area, line, and trail marks. Perform lookup of individual data points along a path, rather than just the first data point.
• Add tooltip handler updates for mousemove events, rather than mouseover events.
• Add getItemBoundingClientRect method to Handler.
• Add standardized canvas getter method to Renderer and Handler to access underlying Canvas/SVG element.
• Update Handler origin method to be getter/setter; previously it was a setter only.
• Fix group item x, y coordinate lookup in resolveItem method.
• Fix circular import among scenegraph code files.