Make //mx and //tmx commands aliases of each other

[eyebo2]

This would just be a small QOL improvement.

Currently when adding a map from TMX on a TM2020 server you use the //tmx add command. And when you're on a TM2 or SM server you use //mx add. But PyPlanet evidently already knows which game the server is running in since it can tell the difference between SM and TM2 and reference the correct website for maps.

Sometimes it's easy to forget which command to use. It would be nice if //tmx and //mx were simply aliases of each other and worked no matter which server you're on, with the controller always going to the correct site to grab maps anyway.