#2376 Jython setItem with index lists didn't check units

[Jeremy Faden]

Ivar noticed that setItem on PyQDataset didn't handle the units property when index lists were used, failing to check to see if a converter is needed.

I should review all setitem branches for this. It seems likely none of the branches do.

[Jeremy Faden]

Also a review of mutability is needed. See https://github.com/autoplot/dev/bugs/sf/2376/demoBugBundle2.jy
which shows how when dd has been marked immutable, it can still be modified by way of its mutable bundled dataset.

[Jeremy Faden]

I've made the DataSetIterator interface have getRank0Value and putRank0Value, which ensure that the units are handled properly (and efficiently at some point).

[Jeremy Faden]

PyQDataSet now checks to see if BUNDLE_1 has been set on the data, allowing this to work:
https://github.com/autoplot/dev/blob/master/bugs/sf/2376/demoSetItemUnits4.jy

[Jeremy Faden]

See https://sourceforge.net/p/autoplot/bugs/2391/ which shows where the change made here slowed things down unacceptably.