These events signal when any threads are running or when all threads have stopped running. This maps to whether the green flag or the stop button should be illuminated in the GUI.
Use it before loading projects so targets don't accumulate when multiple projects are loaded on the same instance.
Move check to see if the clone is the original clone onto the block implementation so all clones can be removed.
Fixes#274
* Provide property to Clone to distinguish "original" clones
* Provide method to clone a clone's properties
* Don't report clones in the UI target list
* Add target info to Thread
* Allow hats to skip clones (for green flag)
* Green flag skips clones
* Implement "create clone" and hat
* Pass the runtime to sprites and clones (for start hats)
* Clone disposal; trigger hats after drawable initializes.
* Separate stop threads for target; fix handling of stop button
* Remove extraneous `skipClones` property
* Add global clone limit
* Don't allow a non-clone to delete itself.
* Rename `cloneClone` -> `makeClone`
* Variable updates in runtime.js
* Synchronous drawable initialization (until we put it back to promises)
* Markup/CSS adjustments
* Move assets to folder
* Strip extra font-family
* More robust handling of project-load fail state
* Move empty project creation to its own function
* Move green flag/stop back out of the tab
* Restore default id
* Remove Fallback Project
* Added A Newline and Removed Fallback Project
* Made The SB2 Project Import Field Fit In More With All Other Textboxes
* Better Description Of SB2 Import Field
* Oops!
* The XML Import Area Doses Not Need To Be Resizable!
* That Didn't Work As Planned
* Now it won't rezize
* Added SB3New
* Add Code For SB3New
* Better 404
* Indentation
* NodeJS complains about quotes
* Moved And Renamed SB3New
* Renamed Refrences
* Prefix With ./
* Typo
* Newline Fix
* Scratch Cat By Default!
* Single Quotes And Max Legth Fixed
* Better Comment Above loadProject
* Move newProject to index.js
* Added Dependincies to index.js
* Deleted newProject.js
* Removed Unneeeded Semicolon
* @param {?string}
* Added SVG For Scxratch Cat
* Now Uses Scratch Cat Offline (REQUIRES PULL REQUEST MADE TO SCRATCH-RENDER TO BE MERGED OR IT WILL NOT WORK)
* Added Stage PNG
* Added Stage Creation
* Fix Sizing Issues
* Import And Compatibility With Less Hacky Image Import (Scratch-Render)
* Import And Compatibility With Less Hacky Image Import (Scratch-Render)
* Fixed Line Length
* Added Navigation Bar
* Added CSS For Drop Down Menus
* Nicer Scale
* Nicer Dropdowns
* Remobved Dropdown CSS (It Didn't Work)
* Add Scratch Player Bar CSS
* Add Scratch Player Bar HTML
* Strip out old script glowing in thread management
* Add new tracking mechanism for glowing scripts
* Track parents and use them to determine script glows
* Use top-block for a thread if there's nothing on the stack
* Remove `console.log`
