Fix division by zero error when importing happens too fast

[tdgroot]

I was writing a very simple import profile and that seemed to happen faster than 0.005 seconds.

Because the delta gets rounded to 2 decimals, it will result as 0 seconds. When calculating how many rows/entities per seconds, the importer will end up dividing by zero. This way the calculations will be legit again, more precise and the displayed delta will now be rounded to 4 decimals instead of 2.

If you have a different opinion on this issue, please let me know!

[tdgroot]

Is this going to be merged or can I close this one?