[mkgmap-dev] [PATCH v1] Reduce number of cuts in multipolygon processing

The patch reduces the number of cuts that must be performed for each inner polygon. The current code performs one cut for each inner polygon. The patch reduces the number of cuts by selecting cut lines that hit more than one inner polygon at once. This has two advantages: 1. The artefacts on the cut lines in Mapsource are reduced because there are less cut lines. 2. The performance of the mp code for large multipolygons is very much dependend on how many cuts must be performed. Tests in Finland with generate-sea=multipolygon have shown a 75%(!) drop on processing time. In case there are no large multipolygons the performance stays quite the same. WanMil