Fixed bad check in MDF_ROOT IO
The check was whether GetBytesRead was exceeding the size of the file. In such case the read was failing. Except this is wrong, as getBytesRead is the number of bytes read and not the offset in the file. If you seeked backwards for example, and then continue reading, the read was failing towards the end for no good reason !
This fix tests the actual offset
Edited by Sebastien Ponce