Apply styles to public and username labels

Though these labels are listed at the top of the LabelsMenu, I wanted to set them off with additional styling.
Add CSS for denoting which component's parameters are being shown
Add new member to track when component is displaying parameters
Deprecate selectedComponent methods
Add icon to ComponentCell that's displaying parameters

This gives a better visual indication of which component in the tree is currently displaying its parameters.
Remove isShowingParameters member
Update CSS rules