[mkgmap-dev] Commit r4191: small DEM performance improvement: reduce number of double[][] allocations

Version mkgmap-r4191 was committed by gerd on Wed, 16 May 2018 small DEM performance improvement: reduce number of double[][] allocations Keep the 4x4 array that is filled for the bicubic interpolation to reduce GC strees http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4191