draft for SSV

[akva2]

[akva2]

all comments addressed. i also drafted how to handle the want ssv, but no viz, hdf5 file.

[kmokstad]

The most relevant scenario is perhaps: We want both ssv and viz-files,where viz-file contains "all" results wheres ssv typically contains the most interesting field only (one chosen scalar field + deformations when relevant).

[akva2]

sure, that's trivial to add when we need it, assuming the most interesting fields means 'primary solutions'.

[akva2]

there we go, always only outputting primary solution to ssv file.