Stop repeatedly setting C attribute handler

It only needs to be set once on program startup and then left alone.

src/tgen-graph.c

@@ -1268,9 +1268,6 @@ TGenGraph* tgengraph_new(gchar* path) {
          * from multiple threads at the same time. this is not a problem when shadow
          * uses dlmopen to get a private namespace for each plugin. */
 
-        /* use the built-in C attribute handler */
-        igraph_attribute_table_t* oldHandler = igraph_set_attribute_table(&igraph_cattribute_table);
-
         g->graph = _tgengraph_loadNewGraph(g->graphPath);
         if(!g->graph) {
             error = g_error_new(G_MARKUP_ERROR, G_MARKUP_ERROR_PARSE,
@@ -1287,9 +1284,6 @@ TGenGraph* tgengraph_new(gchar* path) {
         if(!error) {
             error = _tgengraph_parseGraphVertices(g);
         }
-
-        /* replace the old handler */
-        igraph_set_attribute_table(oldHandler);
     }
 
     if(error) {

src/tgen-main.c

@@ -10,6 +10,7 @@
 #include <igraph.h>
 
 #include "tgen.h"
+#include "tgen-igraph-compat.h"
 
 static void _tgenmain_cleanup(gint status, gpointer arg) {
     if(arg) {
@@ -82,6 +83,9 @@ static gint _tgenmain_run(gint argc, gchar *argv[]) {
         tgen_message("Set SIG_IGN for signal SIGPIPE");
     }
 
+    /* use the built-in C attribute handler. this is set once and then left alone. */
+    igraph_set_attribute_table(&igraph_cattribute_table);
+
     /* parse the config file */
     TGenGraph* graph = tgengraph_new(argv[1]);
     if (!graph) {

src/tgen-markovmodel.c

@@ -880,10 +880,6 @@ static igraph_t* _tgenmarkovmodel_loadGraph(FILE* graphFileStream, const gchar*
     rewind(graphFileStream);
 
     igraph_t* graph = g_new0(igraph_t, 1);
-
-    /* make sure we use the correct attribute handler */
-    igraph_set_attribute_table(&igraph_cattribute_table);
-
     result = igraph_read_graph_graphml(graph, graphFileStream, 0);
 
     if (result != IGRAPH_SUCCESS) {

test/test-markovmodel.c

@@ -2,7 +2,9 @@
 #include <stdint.h>
 
 #include <glib.h>
+#include <igraph.h>
 
+#include "tgen-igraph-compat.h"
 #include "tgen-log.h"
 #include "tgen-markovmodel.h"
 
@@ -87,6 +89,9 @@ gint main(gint argc, gchar *argv[]) {
         return EXIT_FAILURE;
     }
 
+    /* use the built-in C attribute handler. this is set once and then left alone. */
+    igraph_set_attribute_table(&igraph_cattribute_table);
+
     guint32 seed = (guint32)atoi(argv[1]);
     gchar* path = g_strdup(argv[2]);
     gchar* name = g_path_get_basename(path);