ggpie 0.2.0

• Add ggrosepie to create rose pie and donut plot, it can also support single or two variables.

ggpie 0.1.0

• Add ggpie to create 2D pie plot with single group variable.
• Add ggdonut to create 2D donut plot with single group variable.
• Add ggnestedpie to create 2D nested pie plot with two group variables.
• Add ggpie3D to create 3D pie plot with single group variable.