Bug in sorting of phases

[stepanzh]

For mixtures of 4 and 7 components there are kind of bugs when sorting phases by compressibility.

Mix 7 case at 300 K.

[constant]
volume = 1e-6  # meter^3

[range.concentration]  # mole / meter^3
start  = 100
stop   = 20000
length = 100

[range.temperature]  # Kelvin
start  = 250
stop   = 450
length = 100

[stability]
tolerance = 1e-6
maxiter = 1_000

[split]
tolerance = 1e-6
maxiter = 1_000

[mixture]
composition = [
  { nitrogen = 0.00325 },
  { carbon_dioxide = 0.01556 },
  { hydrogen_sulfide = 0.03329 },
  { methane = 0.82829 },
  { propane = 0.08552 },
  { n-hexane = 0.01725 },
  { n-decane = 0.01684 },
]