initial infrastructre laid for solving lps
changed exchange solver interface to no longer take a graph as a constructor argument. exchange solvers now must be created on the heap, configured, and then handed to a caller (the context in the core, e.g.). the Solve member interface now takes a graph as an argument and sets the protected graph_ member. it then calls the virtual, protected member function Solve that is implemented by the various derived solvers.
a little prog solver cleanup
set up osi solver framework. aaaaaaaaaaaaand core dump.
made array_eq work with const pointers
current state throws an exception, not sure why, thanks coin docs..
great success for clp
readded cbc osi, tests passing, but not running bnc