reordered some unit tests
Some tests aren't 100% reliable, and are no longer included in automated testing

These are:

- Histogram and circle-plotting tests: these have inconsistent round-off
  behavior on different arches; specifically 32-bit and 64-bit x86. So both
  plots look fine, but not identical, thus the tests fail

- Streaming tests. These tests have a temporal component, so the loading of
  the host machine can cause a test failure. It's fine pretty much all the
  time on my not-too-new laptop, but this is bad for automated testing

The RUN_ALL_TESTS environment variable can be set to turn all ALL tests