Split or word wrap SVG text for y-axis labels in measurements panel groups

[huddlej]

Description

Originally commented on by @jameshadfield:

think it's worth spending 30 minutes to see if an acceptable solution can be found here. There's heaps of vertical pixel space [1]. Splitting on spaces, hypens, slashes etc should allow a reasonably good result.

[1] at least, there is in the measurements paper's h3n2 dataset I'm using to test. Even when colouring by a unchanging genotype, so there can only ever be one category. Perhaps in some configurations this is different?

@huddlej also noted issues with either very tiny text or text overflowing under different conditions.