3.4.5 rpickle tests

[DreamingRaven]

Added unit tests for serialisation functionality, in an expandable manner to later include more tests, for easier easy and more standard integration with setup.py. Most of these tests will fail for now, but they should offer a good baseline to verify the serialization functionality is working properly during development thus avoiding short throw-away scripts. import seal is purposefully done inside the test functions to both isolate it if not found, so the tests output correctly, and because it is the thing being testd, which to me make more sense to exist withing the test rather than globally like other imports.

Added docker unit tester to make it convenient to run these unit tests in a docker without interaction.

Changed repository main docker builder to be more explicit and to open the container upon completion for inspection. This means we can have multiple co-existing docker files for different system builds and address them individually in future by making it more consistent now.

[Huelse]

Thanks for your work. :)

[DreamingRaven]

no probs, now to tackle the serialization itself!