Enhancements and fixes

Fixes:

• Fixed Cannot read property 'closeTimeout' of null error, #86.
• Arrays are now observed correctly and all elements appear at the right time after mutations. #92.
• All dependencies are bumped to the latest versions #95.

Enhancements:

• Now the object tree view does not collapse after mutations. See GIF.
• Now you can focus on the parent tab by a single click.
• You now see parent tab's URL in the popup.