Change blur approach

[hugolpz]

• Test in SVG blur --> SVG becomes uneditable in inkscape
• Test raster resource blur via esisa/smoothDEM.py --> requires custom script, python2/3, osgeo, scipy dependencies.
• Test gdal .vrt appraoch via How to convert GeoTIFF to grayscale and add gaussian blur? -> requires gdal, sed, and predefined coefs tables.
• Test convert approach, as in Raster output quality to improve. #12 : convert ../output/$(NAME)/trans.gis.tif -blur 3x3 ../output/$(NAME)/trans.png How to restore gdalinfo metadata after ImageMagick processing?