1.0.0

• NEW: Image galleries (#523)
• NEW: Support for canceling input events (#532)
• NEW: Content attachment API (756dcb5)
• NEW: trix-before-initialize event (bee19f5)
• CHANGE: Left-align <trix-toolbar> formatting button groups (6bfb41c)
• CHANGE: Only dispatch trix-initialize event on first connect (5032fd1)
• CHANGE: Remove deprecated indention level editor methods (211eba8)
• CHANGE: Improve trix.css styles for hiding attachment selections (4a1a6aa)
• FIX: Prevent some keyboard commands from inserting text (#534, 8d5294a)