- automatically create sections and store them with the level data.

- added subsector indexing to sections.

This is needed for finding a section from a point.

src/p_maputl.cpp

@@ -470,6 +470,7 @@ void AActor::LinkToWorld(FLinkContext *ctx, bool spawningmapthing, sector_t *sec
 
 	Sector = sector;
 	subsector = R_PointInSubsector(Pos());	// this is from the rendering nodes, not the gameplay nodes!
+	section = level.sections.SectionForSubsector(subsector->Index());
 
 	if (!(flags & MF_NOSECTOR))
 	{