set 'isBeingEdited' property of models

[#68288774]
Crookes Tube should not be in src/models-converted

The models in models-converted should be pristine conversions from the MML. Models should be copied to src/models first if they need to be customized
batch MML converter script in scripts/
Update converted MML files for new properties

The obstacle property 'displayExternalAcceleration' and the atom property 'draggableWhenStopped' have been added since the last commit of the converted files.
force on electrons: make fixed atom nondraggable

[#67843618]
force on electrons: clear trace when flipping charge

[#67843618]