[Coin-lpsolver] GDPO phase 1 dual simplex algorithm

[Lou Hafer]

Rolf,

	I can give you an exact answer for dylp, and some informed speculation
for clp.

	Dylp doesn't provide a dual phase I. For dual phase II, it uses an 
implementation of Maros' dual-GX algorithm, with a few tweaks. Look in 
dy_dualmultipivot.c, starting with dualmultiin, to see how it's done.
	
	Clp uses generalised dual pivoting and artificial bounds (if necessary) 
for dual phase I. Beyond that, you'll need to poke at the code for details.
Look in ClpSimplexDual.cpp, in particular ClpSimplexDual::dualColumn, to see how 
it's done.

							Lou