use grid from image if input grid not set

[sebhahn]

Important for data located on changing swath orbit grid

The second change resample.py, i.e. not_masked = ~mask was needed because for some reason at the 3rd or 4th loop mask has been changed for an unknown reason. Evaluating the mask before the loop solved this strange problem

[wpreimes]

Looks good, does that mean you can use if for swath files now already?

[sebhahn]

in principle yes, still need to check the time series result

[wpreimes]

ok, after you have verified, maybe you can provide a few example swath files (for a study area) so that we can demonstrate how the module works in the docs.