/highlight command that highlights blocks and mobs

Would you please consider adding a /highlight command where you can highlight blocks/entities? It would be very useful for builders (as well as redstoners) as it could be used to create "waypoints" for where certain places/objects are. Say I wanted to put a hidden conduit somewhere in a map but needed to get back to it quickly, I could add a highlight to a block near it and would be able to see it from far away. I know there is the Glowing effect but that only works on entities and not blocks.

Syntax: /highlight ~ ~ ~ <block,entity> <player that sees highlight>

By "block,entity" I mean either a block or entity or both can be specified and highlighted in the specified coordinate position, and by "player that sees highlight" I mean that you could specify which player would see the highlight. you could leave the player specification blank and everyone would see it.

(Idk if Syntax is the right word, I'm a builder, not a redstoner :P)