Bugfix - Socket selection status was not updated properly on file load

This commit adds a missing initialization that caused "Toggle Link (f key)"
not to work properly in case a file with an existing selection status was
opened.

source/blender/blenloader/intern/readfile.c

@@ -1524,6 +1524,22 @@ static void direct_link_nodetree(FileData *fd, bNodeTree *ntree)
 		link->tosock= newdataadr(fd, link->tosock);
 	}
 	
+	/* set selin and selout */
+	for(node= ntree->nodes.first; node; node= node->next) {
+		for(sock= node->inputs.first; sock; sock= sock->next) {
+			if(sock->flag & SOCK_SEL) {
+				ntree->selin= sock;
+				break;
+			}
+		}
+		for(sock= node->outputs.first; sock; sock= sock->next) {
+			if(sock->flag & SOCK_SEL) {
+				ntree->selout= sock;
+				break;
+			}
+		}
+	}
+	
 	/* type verification is in lib-link */
 }