Canvas API maintenance (Blend Modes)

[Joe Andresen]

In addition to ImageOps... We had decided later on that we would drop the strange behavior of the CompositeOperations in Canvas and simply support the JavaFX BlendModes.

We decided BlendMode was a better name than composite because it is consistent with other JavaFX API.

Trivial Change to the API can be seen below:

import javafx.scene.effect.BlendMode;

...

   /**
     * Sets the Global Composite Operation of the current state.
     * 
     * @param op
     */
    public void setGlobalBlendMode(BlendMode op);
    
    /**
     * Gets the Global Composite Operation of the current state.
     * 
     * @return CompositeOperation 
     */
    public BlendMode getGlobalBlendMode();

-Joe