Shape related core functions

[jfacorro]

• begin-contour - "Use the begin-contour and end-contour function to create negative shapes within shapes" 🟥
• begin-shape - "Enables the creation of complex forms"
• end-contour - "Use the begin-contour and end-contour function to create negative shapes within shapes" 🟥
• end-shape - "May only be called after begin-shape"
• load-shape - "Load a geometry from a file as a PShape"
• shape - "Displays shapes to the screen"
• shape-mode - "Modifies the location from which shapes draw"
• shape-modes
• vertex - "All shapes are constructed by connecting a series of vertices"