Robot frontend: Belly editor

[mayacakmak]

The belly rendering has gotten quite complex and messy, it needs some refactoring and rethinking.

First, I propose to:

• Make the belly editor a separate tool from the robot setup, just like the face editor
• Currently all belly screens are editable at once, make it so only one is being edited at a time, give more space
• In the screens created for ACT/DBT I noticed belly screen text formatting using html code in the text (I believe by Samuel), that's a nice idea but doesn't allow for visualizing. Instead formatting options should be separated into simple menus, or some sort of separate CSS editor.
• One thing we should still figure out though is if belly screens are associated with users (like faces) or robots (like it is currently). This might be a separate issue to address both for belly screens and faces.

Once we separate the belly editor we can start adding other belly rendering features mentioned in other issues (text input, grouping/layout, images, icons, custom HTML, etc) both to the backend belly renderer and the new front-end belly editing tool. We also need to:

• Update the Robot setup tool to access the list of available belly screens, add/remove them from robot, rename them, etc.
• Add belly editing tool to front end tools menu