Integrate cropping tool with live vision feed

[jsren]

We will need

• [ ] Add button in UI to begin cropping
• [ ] Draw points over feed (live optional) while cropping
• [ ] Allow undo adding last point (or remove with right-click)
• [ ] Draw instructions over feed during cropping optional
• [ ] Croppings must be saved at least for each pitch, possibly stored for each machine?

It is my intention to use this as a base with which to support clicking to define the pitch outline and mid-points of goals as well.

Be aware that pixel values reported by the mouse handler may not match those on the actual image.