Function: crop

--Usage--
> crop(input: image, height: height_of_new_image, width: width_of_new_image, offset_x: x_position_to_start_crop, offset_y: y_position_to_start_crop)

Shrink an image by cutting off some of the image, starting at the position denoted by the offsets. The resulting image size is specified in the parameters.

--Parameters--
! Parameter		Type				Description
| @input@		[[type:image]]		Image to enlarge
| @height@		[[type:double]]		Height of the resulting image
| @width@		[[type:double]]		Width of the resulting image
| @offset_x@	[[type:double]]		Offset of crop, horizontally
| @offset_y@	[[type:double]]		Offset of crop, vertically