Bas Walraven

Applying the check_norain function to all timesteps

4

In PR #460 the possibility to add a check_norain to a steps nowcast was added, which is very nice! Currently, however, the [check_norain function](https://github.com/pySTEPS/pysteps/blob/master/pysteps/utils/check_norain.py) checks if the entire precip array...