STEP writing

Fixed the STEPControl_Writer.Write() method. Rebuilt the wrappers and uploaded on SVN.
The following code dumps a box on disk:

OCSTEPControl_Writer aWriter = new OCSTEPControl_Writer();
OCTopoDS_Shape shape = new OCBRepPrimAPI_MakeBox(200.0, 150.0, 100.0).Shape();
aWriter.Transfer(shape, OCSTEPControl_StepModelType.STEPControl_ShellBasedSurfaceModel, true);
OCIFSelect_ReturnStatus status = aWriter.Write("C:/sharptest.step");

Implemented by hand the wrapper for the method, solved the problem by allocating a char* buffer where copied the String passed from C#, with this buffer called the native method and released the buffer at the end. Previously the code was just pinning and passing the internal pointer to String:

Standard_CString OCConverter::StringToStandardCString(System::String^ text)
{
pin_ptr textPtr = PtrToStringChars(text);
return TCollection_AsciiString((Standard_ExtString)textPtr).ToCString();
} // OCConverter::ToStandardCString

This method is used at all the String to char* conversions. Will have to think if this functionality is ok and why in the Write() case the internal pointer was overridden when memory was requested from the OpenCascade memory pool by some other object.