Inserts a certain number of bytes into the stream, shifting valid data to the right. The stream's position remains unchanged. (ie. pointing to the beginning of the newly inserted bytes).
Internally this fuction merely acomplishes an Array.Copy(stream,position,stream,position+numberOfBytes,lengthOfValidDataToShift) However, it's much more complicated than this. So this is a pretty useful function. The newly created space is uninitialized.