The INTERACTIVE_CROP function will allow the user to select a
spatial sub-region of the provided image that is to be cropped.
The function will create a window and display the image provided
for the user to interact with.
Either a 1- or 3-band image that is to be interactively cropped.
A 1- or 3-band extracted subimage will be returned to the calling
Written by: Carl Salvaggio
Original Code: Oct 20, 2010