v1.1.0

• Set angular as a peer dependency instead of as a normal dependency (allowing for better user control of the angular version) (Issue #52)
• Add start-expanded="'recursive'" to cause the entire tree to be expanded initially (instead of just the top-level, which setting the value to true previously allowed) (Issue #56)
• Add track by to remove $$hashKey attributes (Issue #59, PR #60)
• Add .empty to the class list of nodes that are expandable but have no children (Issue #63)