fix histogram plot failure on float('inf')

[jeromedockes]

fixes #1134

this is a quick fix for #1134

later we can improve handling of infinite or very large values by

• excluding them from the computation of summary statistics (?)
• excluding them while setting the bounds of the shown histograms to avoid unhelpful histograms with only one bar

however this requires taking care to make sure that the user realizes those outliers have been discarded so may take a bit more discussion. So I suggest we avoid crashing for now so that the release 0.3.2 does not depend on solving these more subtle choices

[Vincent-Maladiere]

LGTM!