New heuristics for MCF algorithms (#340)
and some implementation improvements.

- A useful heuristic is added to NetworkSimplex to make the
initial pivots faster.
- A powerful global update heuristic is added to CostScaling
and the implementation is reworked with various improvements.
- Better relabeling in CostScaling to improve numerical stability
and make the code faster.
- A small improvement is made in CapacityScaling for better
delta computation.
- Add notes to the classes about the usage of vector<char> instead
of vector<bool> for efficiency reasons.

 AM_CXXFLAGS = $(WARNINGCXXFLAGS)

 AM_CPPFLAGS = -I$(top_srcdir) -I$(top_builddir)

 LDADD = $(top_builddir)/lemon/libemon.la

 EXTRA_DIST = \

 	CMakeLists.txt \

 	digraph.lgf

 noinst_PROGRAMS = \

 	arg_parser_demo \

 	graph_to_eps_demo \

 	lgf_demo

 arg_parser_demo_SOURCES = arg_parser_demo.cc

 graph_to_eps_demo_SOURCES = graph_to_eps_demo.cc

 lgf_demo_SOURCES = lgf_demo.cc