Fixed fields

Fixed fields for ice scoring -- in binary unless otherwise noted

• seaice_gland5min -- global land mask, 1 byte per cell, 1/12th degree, N-S, E-W on the half-integral pts
  • 0 = ocean, 157 = land, 195 = coast (indeterminate between land and ocean -- NCEP analysis gave concentrations here, but values are less reliable)
• seaice_alldist.bin -- binary floats of distance to land. Used for some filterings.
• skip_hr -- global byte mask, as seaice_gland5min
  • ... values
• skip_lowres -- global 1/2 degree byte mask, otherwise as skip_hr