noise detection of time step

noise utility tries to detect uniform time step by comparing to previous time directories:

At time 0.277259999999 previous time:0.277255 difference:4.999998999999367e-06 deltaT:5.000000000005e-06 relative difference:2.000011267710988e-07

This goes wrong when there are not enough timePrecision or the start time is late so we loose precision.