[Osi] milp support in OSI

[Lou Hafer]

Folks,

	I'm with Laci here.  We should have removed Osi::branchAndBound years
ago.  Osi is has become far too bloated.  There's just no excuse for a class
with 200 public methods.  Yet more functions will not make OsiSolverInterface a
better, more useable design.  What's needed is some thought on how to properly
divide it into a coherent base class and coherent subclasses.

	A good first step would be that we all stop adding new interface
routines on the spur of the moment, and start working on the basis of consensus
addition / modification / deletion.  The debate that comes out of that process
would likely get us thinking on how to properly organise the existing OSI
methods.

							Lou