Explain the classical way to compile qDFTgraph.
Check for tcl.h header.
Test script used to evaluate the library.

Run testlib with several parameters and compute statistics on the
results.
Add memory footprint measurement to test_lib.
Add AM_PROG_AR for automake 1.12+
Print the number of nodes and edges.

* include/qdft/manager.hh,
* include/qdft/manager.hxx: Provide get_graph_size method.

* include/qdft/qdft.hh,
* include/qdft/qdft.hxx: Provide get_graphs_size method.

* src/test_lib.cc: Print total number of nodes and edges in addition to
  memory footprint.
Update Doxyfile for doxygen 1.8.
Improve project configuration.

* configure.ac: Add option disable-documentation and define HAVE_TCL_H
  if tcl8.5/.tcl.h is found.
* include/Makefile.am: Compile qdft_wrap.cxx iff. HAVE_TCL_H is defined.
Reactivate block_transfer.
Implement lazy evaluation for C2 step.
Fix integer overflow with simplification rule 2.
Mark estimation for the target node as unknown in set_edge_quantity.
Fix precision issue with simplification rule 2.

* include/qdft/manager.hxx: Take the minimum between e1 and e2 in
  simplification rule 2 when e3 is equal to 0.

* src/example.cc: Add an assert to check for simplification rule 2.
Merge branch 'next' of https://github.com/joudinet/qdftgraph into next