TODO list before major work

[TheCherno]

• [x] Add ApplicationSpecification with custom working directory (to fix Sandbox not working out of the box)
• [x] Textures in SpriteRendererComponent don't get serialized
• [x] Merge dev into master again (because of PRs)
• [x] Save feature (#516)
• [x] Better circle collider visualization (#517)
• [ ] Hazelnut scene titles (#528)
• [ ] Readme/logo stuff (#519 and #541)
• [ ] Fixed physics collider visualization offset (#555)