OcdFileImport: Warn about unsupported virtual gaps

Line objects in .ocd files can contain virtual gaps, i.e., gaps that
interrupt the line but keep the object as a single object.
Mapper does not yet support virtual gaps and thus ignores them when
importing .ocd files.
Issue a warning that virtual gaps in line objects are not supported.

Author: dl3sdo

src/fileformats/ocd_file_import.cpp

@@ -2163,6 +2163,11 @@ void OcdFileImport::fillPathCoords(OcdImportedPathObject *object, bool is_area,
 	{
 		object->coords[i] = convertOcdPoint(ocd_points[i]);
 		setPointFlags(object, i, is_area, ocd_points[i]);
+		if (ocd_points[i].x & Ocd::OcdPoint32::FlagGap)
+		{
+			// Virtual gaps are not supported
+			addWarningOnce(tr("Virtual gaps in line objects are not supported."));
+		}
 	}
 
 	// For path objects, create closed parts where the position of the last point is equal to that of the first point

src/fileformats/ocd_types.h

@@ -1,5 +1,5 @@
 /*
- *    Copyright 2013, 2015-2019 Kai Pastor
+ *    Copyright 2013, 2015-2019, 2024 Kai Pastor
  *
  *    This file is part of OpenOrienteering.
  *
@@ -231,7 +231,8 @@ namespace Ocd
 		{
 			FlagCtl1 = 0x01,
 			FlagCtl2 = 0x02,
-			FlagLeft = 0x04
+			FlagLeft = 0x04,
+			FlagGap  = 0x08
 		};
 
 		// Flags in Y coordinate