Handle Negative coordinates

[MattReimer]

We currently fail on rasterman copy when any of the coordinates are negative. We need to either handle this more gracefully and return why something is invalid or fix it so that negative coordinates are ok:

if (fLeft <=0)
    return LEFT_ERROR;

if (fTop <=0)
    return TOP_ERROR;

if (nRows <=0)
    return ROWS_ERROR;

if (nCols <=0)
    return COLS_ERROR;