[interp_relperm] Add support for family 2 output

[berland]

The two commits should be reviewed independently, and merged, not squashed.

Support for family 2 input is a different PR.

[codecov-commenter]

Codecov Report

Merging #382 (5b8a3d2) into master (e4edb03) will decrease coverage by 0.01%.
The diff coverage is 91.66%.

@@            Coverage Diff             @@
##           master     #382      +/-   ##
==========================================
- Coverage   85.47%   85.45%   -0.02%     
==========================================
  Files          42       42              
  Lines        6107     6107              
==========================================
- Hits         5220     5219       -1     
- Misses        887      888       +1     

Impacted Files	Coverage Δ
src/subscript/interp_relperm/interp_relperm.py	82.16% <91.66%> (-0.55%)	⬇️

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[eivindsm]

Pr looks good. The possible combinations of saturation kws for family ii is quite extensive. For family i the script requires both SWOF and SGOF to be present, have you considered how to implement the similar requirement for family ii? Eg all possible combinations of SWFN, SGFN, SGWFN, SOF2, SOF3, SOF32D, SWF3, SGF3, SOF3 (IKU3P and ODD3P options)

[berland]

See equinor/pyscal#100

Those keywords are not supported by pyscal but can be added. The more advanced keywords are not planned to be supported by pyscal.

[eivindsm]

LGTM