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.

Resulting image can be bigger than the original, if offset_x or offset_y are negative, or if width or height are bigger than the original width and height.

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

