IndexWriteIterator produces incorrect frames for 4Byte index mode

The increment operator for IndexedWriteIterator uses the enum
IndexMode to determine how many bytes to increment the pointer.  If
the index size is IM_NONE, IM_1B, or IM_2B, the pointer is incremented
the correct 0, 1, or two bytes respectively.  If the index size is 4
bytes, the pointer is only moved three bytes since the value of IM_4B
is 3.  Here's a possible fix:

enum IndexMode
{
IM_NONE = 0,
IM_1B = 1,
IM_2B = 2,
IM_4B = 4
}

Original issue reported on code.google.com by jadamcrain on 3 Oct 2011 at 2:19

dlsantos / dnp3

IndexWriteIterator produces incorrect frames for 4Byte index mode #27