fixed user defined grid_file in FDR calculation

[wusixer]

fiexed "ufunc 'bitwise_and' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe'' " error caused by

prob_grid = prob_grid[(np.sum(prob_grid, axis=1) > 1.) & np.sum(prob_grid, axis=1) < 0]

when passing in user defined grid_file. In the above code, the 'bitwise_and' was not comparing values of the same type.