Explicit MSGV

[vurvdev]

Want an explicit "Minimum supported gmod version", that will be on the README file and if a server loads with a wiremod version newer than this, it'll give off an ErrorNoHalt.

Fixes and compatibility with these version differences won't be guaranteed.

[marchc1]

I think that it should print something in chat alongside the ErrorNoHalt when the user loads in, would make it a bit more obvious to users + owners IMO