Use XDG special directory instead of hard-coding ~/Pictures

Fixes #22

main.c

@@ -346,7 +346,7 @@ on_open_directory_clicked(GtkWidget *widget, gpointer user_data)
 {
 	char uri[270];
 	GError *error = NULL;
-	sprintf(uri, "file://%s/Pictures", getenv("HOME"));
+	sprintf(uri, "file://%s", g_get_user_special_dir(G_USER_DIRECTORY_PICTURES));
 	if (!g_app_info_launch_default_for_uri(uri, NULL, &error)) {
 		g_printerr("Could not launch image viewer: %s\n", error->message);
 	}

process_pipeline.c

@@ -350,7 +350,10 @@ process_capture_burst(cairo_surface_t *thumb)
 	char timestamp[30];
 	strftime(timestamp, 30, "%Y%m%d%H%M%S", &tim);
 
-	sprintf(capture_fname, "%s/Pictures/IMG%s", getenv("HOME"), timestamp);
+	sprintf(capture_fname,
+		"%s/IMG%s",
+		g_get_user_special_dir(G_USER_DIRECTORY_PICTURES),
+		timestamp);
 
 	// Start post-processing the captured burst
 	g_print("Post process %s to %s.ext\n", burst_dir, capture_fname);