This function sets the provided Tcl object as
comment to the specified Collection object. This "comment" (Tcl object)
can contain anything that the user wants to store with this Collection.
This comment
object will be saved allong the Collection, if the Collection is saved.
This is the primary difference of comment towards associated
information that can be inserted with
tip_GetAssociatedInfo/tip_SetAssociatedInfo.
Return Value:
The return value from this function will be a standart Tcl completion
code (of type int) with one of the values TCL_OK and TCL_ERROR. If the
requested Collection exists and the comment Tcl object is
successfully associated with the Collection, then TCL_OK will
be returned. In case of an error, the return value will be TCL_ERROR and
an error message describing the error will be left at the current Tcl
interpreter (CDM_Interp).