+ topo: merge runMultilookGdal() into runMultilook() with new argument "method" to control to use isce Looks module (averaging) or gdal_translate (extraction; default, same as before).
+ topo: call gdal2isce_xml.py so that xml file for multilooked data are always generate. This fix the warning message from gdal_translate: "Warning 1: Geotransform matrix has non rotational terms"
+ topo: skip multilooking if the data file has vrt/xml file missing, which sometimes happens to incLocal and shadowMask (don't know the cause yet; I used GPU version).
+ crossmul/resampleSlc: re-organize module import at the top of scripts
@falkamelung noted a race condition in #106 due to non-atomic directory
checking followed by os.makedirs. This pattern exists in many places
in the codebase so I went ahead and replaced the rest of them.
The new exist_ok usage should be terser and more idiomatic.
Zhang Yunjun
Ryan Burns
Eric Gurrola