This allows compilation with older versions of boost (>=1.38), which in
some sistems are the only option. This commit also removes the linking
of the boost_graph shared library, since none of its symbols are
actually required.

Fix compilation warnings with boost 1.40, remove unnecessary files, fix
autoconf macros and link with "boost_graph".

This also raises the minimum boost version to 1.40.

This fixes bug where boost overlay files were not being used, when not
compiling from source dir.

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

* change from HashedDescriptorMap to vector_property_map in several
  algorithms to save memory and increase speed in the most common
  case, where the graph is unfiltered.




git-svn-id: https://svn.forked.de/graph-tool/trunk@102 d4600afd-f417-0410-95de-beed9576f240