Function: insert_image

--Usage--
> insert_image(base_image: image, inserted_image: image, offset_x: coordinate, offset_y: coordinate, background_color: color)

Insert an image inside another image.

The inserted image can be put outside the bounds of the base image. The resulting image will be widened accordingly.

--Parameters--
! Parameter				Type				Description
| @base_image@			[[type:image]]		Image that serves as the canvas
| @inserted_image@		[[type:image]]		Image inserted on top of the base image
| @offset_x@			[[type:double]]		Offset of insertion, horizontally, in pixels
| @offset_y@			[[type:double]]		Offset of insertion, vertically, in pixels
| @background_color@	[[type:color]]		Background color, optional, defaults to transparent

