Replacing objects under model control using the REPLACE operation

- Added new dynamic object operation: REPLACE (command code of 3)

In this mode, _original_id specifies the object ID of the original to copy
and _new_id must be set to specify the object ID of the object that will
be replaced.

The new object will hence get the ID _new_id.

The _x,_y and _new_panel columns are ignored in this mode.

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idkbase note 48