more flexibility with the /clone command

Adding an argument that allows a cloned structure to replace only a specific block (similar to how the filtered argument works when cloning a structure) would make the clone command much more useful for building and would allow for stuff that were previously only possible by running a bunch of individual /setblock commands with the replace argument. Also, having the ability to set more than just one block when using the filtered argument would be great way to add some much need functionality.