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

 prefix=@prefix@

 exec_prefix=@exec_prefix@

 libdir=@libdir@

 includedir=@includedir@

 Name: @PACKAGE_NAME@

 Description: Library of Efficient Models and Optimization in Networks

 Version: @PACKAGE_VERSION@

 Libs: -L${libdir} -lemon

 Cflags: -I${includedir}