Called when a variable is edited on an Entity (called by
Edit Properties... menu), to determine if the edit should be permitted.
See Editable entities for more details about the system.
1 Entity ent
The entity being edited.
2 Player ply
The player doing the editing.
3 string key
The name of the variable.
4 string val
The new value, as a string which will later be converted to its appropriate type.
Return true to allow editing.