made Network.crop() work with bounds outside min/max of network
made Network.crop() work with bounds outside min/max of network

scikit-rf/scikit-rf,jhillairet/scikit-rf,temmeand/scikit-rf,scikit-rf/scikit-rf,temmeand/scikit-rf,temmeand/scikit-rf,jhillairet/scikit-rf,jhillairet/scikit-rf