[mkgmap-dev] Commit r4786: merge from low-res-opt branch

Version mkgmap-r4786 was committed by gerd on Wed, 23 Jun 2021 merge from low-res-opt branch - new options --simplify-lines, --simplify-polygons, and --improve-overview - better handling of contour lines and lines in overview map (less zig-zagging/diverging of parallel lines) - direction flag is used with extended types (effects results of --allow-reverse-merge) - option --allow-reverse-merge is now also used for non-routable lines - better detection of obsolete points caused by rounding - different method to calculate and preserve "needed" points allows better line/polygon simplification http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4786