0025689: IGESCAFControl_Writer crash in constructor.

0025689: IGESCAFControl_Writer crash in constructor.

Cause of bug is that the IGESData_BasicEditor is created before an initialization of IGESControl_Controller::Init(). IGESData_BasicEditor cannot find template "iges", so the model is still empty after creation.

1) Added a default constructor to the IGESData_BasicEditor. Can be initialized via Init() method.
2) Added some null checks in the places, where are provided access to the model (IGESData_BasicEditor's member).
3) Initialization of the IGESData_BasicEditor was placed after initialization if the IGESControl_Controller.