Add "graph_tool.hh" convenience include file

src/graph/Makefile.am

@@ -63,6 +63,7 @@ libgraph_tool_core_la_include_HEADERS = \
     graph_properties_map_values.hh \
     graph_python_interface.hh \
     graph_selectors.hh \
+    graph_tool.hh \
     graph_util.hh \
     hash_map_wrap.hh \
     histogram.hh \

src/graph/graph_tool.hh

+// graph-tool -- a general graph modification and manipulation thingy
+//
+// Copyright (C) 2006-2016 Tiago de Paula Peixoto <tiago@skewed.de>
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 3
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef GRAPH_TOOL_HH
+#define GRAPH_TOOL_HH
+
+#include "graph.hh"
+#include "graph_filtering.hh"
+#include "graph_properties.hh"
+#include "graph_selectors.hh"
+
+#endif //GRAPH_TOOL_HH