ISMIP7 input routines

[erwinlambert]

Get the model to run with provided ISMIP7 forcing files without the need for manual preprocessing:

• Ocean forcing:
  • thetao (t,z,y,x) with files per ~50 years
  • so (t,z,y,x) with files per ~50 years
• SMB forcing:
  • acabf climatology (y,x); no official ISMIP file, but may be available through SMBmip
  • acabf-anomaly (m,y,x), 1 file per year with monthly values
  • dacabfdz (y,x), 1 file per year, contains NaNs!
• Climate forcing (ts or tas?):
  • ts climatology (y,x); no official ISMIP file, but may be available through SMBmip
  • ts-anomaly (m,y,x), 1 file per year with monthly values
  • dtsdz (y,x), 1 file per year, contains NaNs!