1.9.0

Added

• Add brand new YAML storage format (thx @matthiashamacher)
• Add new argument source=xxx to translate command. This defines what locale should be used as base language for translations.
• Add new option --empty to export command. This only exports translation entries that are not yet 100% translated.

Changed

• Improved error outputs when loading configuration files without existing translation-sets. There will now be a better error message for this.
• Add special keyword dev to composer to show this is a dev-tool and ask if --dev should be used to install it. (thx @xabbuh)