changing colormap range

[moontrip]

This PR intends to resolve VEuPathDB/web-components#454. Made a mistake to resolve this in a very complex manner but later much simpler solution was found. Also, it is worth noting that while I was working on the colormap range, I noticed that the decimal points in the colormap's tick labels were often too long, so I have set it up to be 2 decimal points at a web-components PR, VEuPathDB/web-components#464. Finally, I found that seriesGradientColorscale was not typed so I also fixed it.

Two logics are currently utilized to find out the colormap range: a) no filter case: taking Min/Max between displayMin/Max and rangeMin/Max using the metadata of the overlay variable; b) with filter(s) (subsetted): taking Min/Max between computed data-based Min/Max and displayMin/Max from the metadata of the overlay variable. I saw that there is a work in progress to have a filter-aware metadata by Danielle, but it appeared to me that it is still underway.

Some screenshots are attached in the following (GEMS1 data): BMI-for-age-z-score has displayMin/Max of (-30, 20) and rangeMin/Max of (-15.3, 273.91).

a) No filter is used: in this case, range becomes (-30, 273.91)

b) with filters: data-based Min/Max is (-11.05, 143.33)

c) Age, matched case for the overlay variable with filters: Sequential colormap. No displayMin/Max; data-based Min/Max is (33, 56), thus final range becomes the data-based Min/Max

[bobular]

Hi @moontrip - will you make a new PR in the monorepo for this?