This removes reverse_graph.hpp, reverse_graph.hpp and copy.hpp, and
introduces some modifications in graph_adaptor.hh. This modification
fixes compilation problems across different boost versions.

This also keeps compatibility with earlier versions of boost.

This also maintains compatibility with older boost versions.

This commit splits libraph_tool into different libraries:
 
   - libgraph_tool_core
   - libgraph_tool_clustering (*)
   - libgraph_tool_community (*)
   - libgraph_tool_correlations (*)
   - libgraph_tool_distance (*)
   - libgraph_tool_generation (*)
   - libgraph_tool_layout (*)
   - libgraph_tool_misc (*)
   - libgraph_tool_stats (*)

It also adds the python sub-module 'test', which provides extensive unit
testing of the core functionality. The core library is fully functional
and all test pass successfully.

(*) -> module needs to be ported to new refactoring, and does not yet build

git-svn-id: https://svn.forked.de/graph-tool/trunk@1 d4600afd-f417-0410-95de-beed9576f240