v0.6.0

The JS package (#46) is now available from npmjs.com/package/@mozilla/l10n.

• Update & simplify message data model (#39)
• Add MF2 support (#40)
• Add a compact JSON representation for messages (#41)
• Merge .message.data and .resource.data as .model to fix circular imports (#44)
• Allow // line comments in messages.json (#51)
• Add paths.all_locales (#52)
• Various resource format fixes (#58)