Change Immutable status to ReadOnly, which makes it easy to set value
in script, but still block editing in property view by default. This is
to discourage user editing support using property editor, because
SubShapeBinder requires relative link correction.
* in the undo/redo list use an object's label and not the internal name
* check by the transaction ID instead of name to open a transaction to make the workbenches independent of implementation details of the core system
* when rejecting a task do not call undo() because this is not the same as aborting a pending transaction
* this also fixes the warning: <App> Document.cpp(1182): Cannot commit transaction while transacting
