Package Updates and Bug Fixes

What's New

• Entity and Relation templates for the JSON editor
• Right-click to remove and undo remove menu
• Canvas no longer resizes itself on click, a fit button is implemented to resize to entire graph

What's Changed

• Update node.js and npm versions by @iris-liu0312 in #7
• Update packages and fix errors by @iris-liu0312 in #8
• Bug fixes by @iris-liu0312 in #9

Full Changelog: v0.5...v0.5.1