1. Removed duplication of code in stage component to avoid future
     potential divergence. Now just selectively applying styling based
     on states of zoomed, colorPicking, and question.

  2. Fixed bottom border getting chopped in zoomed mode by adding margin
     and adjusting height/width accordingly.

  3. Removed shouldComponentUpdate from stageHeader as suggested from code
     review. Added ignore lint warning suggesting change to stateless function.

Target specific palette

Use relative path to load extension assets

Append sprite name to monitor label for sprite-specific monitors.

Update react-responsive to the latest version 

Update react-test-renderer to the latest version 

Fix waveform in sound editor in Firefox

Register music extension assets

Update react to the latest version 

Update react-dom to the latest version 

Update enzyme-adapter-react-16 to the latest version 

Update react-tabs to the latest version 

Warn user before navigating away/unloading

Refresh workspace with sprite-specific blocks when sprite changes

Prevent deleting a sound from exploding

chore(package): update eslint-plugin-react to version 7.5.1

firefox doesn't like comma (,) in svg path, so I change comma to space