introduced formatString from recent work in BDV for
CATMAIDRandomAccessibleInterval which enables more flexible CATMAID
sources

added simplified and more efficient  Downsampler from my TrakEM2 code and
renamed the ImgLib2 Downsampler to GenericDownsampler, TODO find a better
place for GenericDownsampler because it is useful code, just not needed
here

entirely rewrote ScaleCATMAID, input parameters are minimal and the scaler
identifies sources and dimensions by itself

moved utility methods from Tiler into Util to enable catmaid-scale.jar
being an ImgLib2 free package (no dependencies except Java standard)