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.

 if WANT_TOOLS

 bin_PROGRAMS += \

 	tools/dimacs-solver \

 	tools/dimacs-to-lgf \

 	tools/lgf-gen

 dist_bin_SCRIPTS += tools/lemon-0.x-to-1.x.sh

 endif WANT_TOOLS

 tools_dimacs_solver_SOURCES = tools/dimacs-solver.cc

 tools_dimacs_to_lgf_SOURCES = tools/dimacs-to-lgf.cc

 tools_lgf_gen_SOURCES = tools/lgf-gen.cc