Don't connect dots unless they are adjacent in the data

[openjck]

This is a rare issue that can make affected charts somewhat confusing. Imagine that a particular population is only in the data on two days: January 1, 2017 and January 1, 2019. Ensemble will show a line connecting those two points, even though that population isn't actually in the dataset for most of that time.

This can happen on the Top Languages chart. The chart shows only the top 5 languages. For some time, zh-CN and es-ES were fighting for 5^th place. zh-CN overtook es-ES exactly twice: once in December 2018 and once in April 2019. It wasn't in 5^th place in January, February, or March. Nonetheless, Ensemble drew a line between December 2018 and April 2019 for zh-CN, implying that it was one of the top 5 languages that whole time when it was not.

One solution might be to show separate dots in these situations and only draw lines between dots that represent consecutive dates in the dataset.