Some formatting issues in the Details table

[GregorCH]

• all numeric columns display a left-aligned string "--" for missing values which looks weird.
• An infinite gap is not displayed consistently in the Gap column if the infinity is different from 1e+20, probably a hard-coded value somewhere
• sometimes tiny differences in the primal bounds/dual bounds do not have a visible coloring. Maybe use some minimum redness/greenness to visibly distinguish instances where nothing changed from those where it did.

[fschloesser]

I addressed the points. I hope i did not miss anything.