ReadLEUint in ZipFile.cs needs a cast

Currently, it is:

uintReadLEUint()

{

    return(uint)(ReadLEUshort()|(ReadLEUshort()<<16));

}

But that causes exceptions if overflow check is enabled.  I changed it to this:

    return(ReadLEUshort()|((uint)ReadLEUshort()<<16));