Modify the interface of Suurballe (#266, #181)

- Move the parameters s and t from the constructor to the run()
function. It makes the interface capable for multiple run(s,t,k)
calls (possible improvement in the future) and it is more similar
to Dijkstra.
- Simliarly init() and findFlow(k) were replaced by init(s) and
findFlow(t,k). The separation of parameters s and t is for the
future plans of supporting multiple targets with one source node.
For more information see #181.
- LEMON_ASSERT for the Length type (check if it is integer).
- Doc improvements.
- Rearrange query functions.
- Extend test file.

 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