Timeline workflow improvements

This week, we made a few improvements to the timeline that will increase your productivity in Fable!
- Setting a layer’s parent now overwrites any existing parent relationships. You no longer have to remove the existing parent connection to create a new connection.
- We added a keyboard shortcut for zooming in ('=') and out ('-') of the timeline.
- The keyboard shortcuts for moving the playhead to the next/previous keyframe ('g'/'f') now only account for keyframes currently visible on the timeline.
Fixes & Improvements
- Audio layer volume now uses decibel (db) units instead of a percentage.
- Shape tools are now hidden while in path editing mode.
- Fixed a bug that caused the app to crash when using the color picker with multiple layers.
- Fixed a bug that caused adjusting the anchor point of a scene to create position keyframes on the children layers.
- Fixed a bug that caused paths with a trim setting of start: 0% and end: 100% to be hidden on the canvas. Now, these settings display the full path.
- Fixed inaccurate bounding boxes around straight 2-point paths. Now you can align straight paths vertically and horizontally.
- Fixed a bug that caused the effects panel to sometimes overlap with the inspector.
- Fixed a bug that raised an error notification when new users signed up.