We need more tests of `{local_}calculate_temperature`

[mabruzzo]

While working on PRs #153 and #160, I became aware that we don't really have any answer-tests of calculate_temperature when using tabulated-mode - for example, I broke something and none of the tests seemed to catch it.

It's been a while since I looked at this, but I seem to recall that the test coverage of the other calculate_ functions is also a little sparse.