phase I solver

This program is used to find a strictly feasible starting point for a
sandard LP, i.e.
minimize     c'x
subject to    Ax == b
x >= 0
internal method

internal method used by phase I solver, conduct the centering steps --
solve the log-barrier problem.
main procedure of LP solver

Solve the problem:
minimize    c'*x
subject to   Ax == b
x >= 0
given A, b and c, return optimal point x*
LP solver with a given x0

With a given strictly feasible starting point x0, solve the LP problem.