related with https://github.com/isce-framework/isce2/pull/97
+ move cpx cohe calculation code from main() to estCpxCoherence()
+ move computeCoherence import from the top to the inside of estCpxCoherence(), to avoid import error/warning sometimes.
+ fix typo in the default value of --cc option from 'fine.cori.full' to 'fine.cor.full'
+ FilterAndCoherence: skip filtering if input filter strength <= 0 and use original phase for coherence estimation
+ Stack: do not add filt_ prefix to output file if input filter strength <= 0
+ 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.
* Fix burst loading in estimateAzimuthMisreg.py
Within the for loop that starts at line 82, looping through range(minBurst, maxBurst) misses the burst with the maximum burst number. In cases where only one burst in a swath is used, the script fails at line 90 when .getWidth() is called on an empty xml. This issue can be fixed by adding the line maxBurst = maxBurst + 1
* Fix burst loading in estimateRangeMisreg.py
Similar to estimateAzimuthMisreg.py, calling range(minBurst,maxBurst) at line 185 will lead to an empty list and the some bursts not being loaded unless line 181 is changed from maxBurst = maxBurst - 1 to maxBurst = maxBurst +1