fix line interface
add Canvas#getColorIndex
add Canvas#getRawData
add internal canvas property
add line segment clipping
add Canvas#polygon
remove Canvas#paint filled option
remove Canvas#plotter
change color interface
add Canvas#copy
add Canvas#paste
add color setter
class modularization
update examples
fix Canvas#paint when background color and fill color are same
comment
add CanvasRGB, CanvasRGBA
fix Canvas#polygon
add Canvas#draw
add Canvas#mask