we had a custom wrapper for bandjoin(), but bandrank(), a function with
an almost identical interface, did not ... this was confusing
bandrank() now has a custom wrapper too ... this breaks API
unfortunately, but hopefully very few people were using this thing and
it's better to make this change as soon as possible
we had both a class member bandjoin, and an instance member
Vips.Image.bandjoin([i1, i2, i3..])
i1.ibandjoin([i2, i3..])
this was confusing and annoying ... get rid of the class one and just
use bandjoin everywhere, so this is now the way to do it:
i1.bandjoin([i2, i3..])
oh argh class and instance methods are in the same namespace, so we have
to rename the instance one as ibandjoin
also, start adding a test for arrayjoin
It's not widely packaged in Linux distributions, and none of the VIPS
Python code requires Python 3 semantics from any of the builtins future
was replacing.