Flag isolated rework

• reworked flagIsolated, to fix #358 (closed)
• @schaefed - i did start from scratch and didnt continue your implementation idea - i could not think of an easy way implementig the mechanics on the numpy level of things, (even with np.stride_tricks available now), since the undetermined size of the window views from not harmonized windows somehow poses a real problem. Also, rolling.sum is quite optimized i think ...