Initially developed by Sandro Santilli <strk@keybit.net>

This plugin shares directives with the "postgis" one,
with the following differences:

 - "raster_field" replaces "geometry_field"

 - "raster_table" replaces "geometry_table"

 - "prescale_rasters" replaces "simplify_geometries"

 - "use_overviews" introduced

 - "clip_rasters" boolean introduced, defaults to false

 - "band" introduced, with same semantic of the GDAL driver