Meta Zone -> Metazone

[sffc]

@Manishearth, @samchen61661, and @markusicu prefer Metazone as one word instead of Meta Zone as two words.

I have a slight preference for two words to be consistent with Time Zone, but there are valid arguments that Metazone should be one word, including:

1. "Meta" is a prefix, not an adjective (although some dictionaries do list it as an adjective)
2. UTS 35, while inconsistent, tends to use one word more often than two words

As part of this, I'd like to also make sure that camel case MetaZone is Metazone and snake case meta_zone is metazone.

[robertbastian]

nevermind