[mkgmap-dev] Commit r4373: code cleanup using hints from sonarlint, no change in output expected

Version mkgmap-r4373 was committed by gerd on Sun, 17 Nov 2019 code cleanup using hints from sonarlint, no change in output expected - use more lambdas and computeIfAbsent - merge nested if-then clauses - improve formatting - remove OsmReadingHooksAdaptor, add defaults to interface OsmReadingHooks http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4373