Thorough redesign of the LP/MIP interface (#44)

- Redesigned class structure
- Redesigned iterators
- Some functions in the basic interface redesigned
- More complete setting functions
- Ray retrieving functions
- Lot of improvements
- Cplex common env
- CLP macro definition to config.h.in
- Update lp.h to also use soplex and clp
- Remove default_solver_name
- New solverName() function in solvers
- Handle exceptions for MipCplex test
- Rename tolerance parameter to epsilon
- Rename MapIt to CoeffIt
- Lot of documentation improvements
- Various bugfixes

 if WANT_TOOLS

 bin_PROGRAMS += \

 	tools/dimacs-to-lgf

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

 endif WANT_TOOLS

 tools_dimacs_to_lgf_SOURCES = tools/dimacs-to-lgf.cc