Minecraft renames

BUR #3606 has been approved by @Hillside_Moose.

rename steve? -> steve_(minecraft)
rename alex? -> alex_(minecraft)

I can't find any sources confirming that "Steve" is actually named "Steve?". Same thing for Alex.
If it was a thing back in 2012 then it must have been short-lived.

EDIT: The bulk update request #3606 (forum #173871) has been approved by @Hillside_Moose.

Alternatively we could also just use steve and alex since neither of them are being used, but that might be a little ambiguous.

Back when Minecraft was still in beta, people asked Notch if the default character had a name. His response: "Steve?".

Minecraft is no longer Notch's IP, so might as well change it to the official name.

The bulk update request #3606 (forum #173871) has been approved by @Hillside_Moose.