[Meta] Inspector features

[claus]

• [ ] Summary of the number of various display objects types
• [ ] Button to invalidate and repaint the stage several times
• [ ] Editable properties of display objects
• [ ] Visualization of bounding boxes of display objects on stage, different colors for different types, click on bounding box highlights corresponding item in list and vice versa
• [ ] Visualization of display objects on stage, dim all other objects except the selected one
• [ ] Show selected display object without transforms in separate panel
• [x] Button to advance to next frame when paused
• [x] Button to mute sounds

[claus]

@tobeytailor cwahlers: one idea i had last week was extending the inspector so that we can use it on dekstop while the actual content is running on a mobile device @tobeytailor cwahlers: maybe we can extend the remote debugging protocol for that