Fixes and closes #6
Upgrades dependencies
Test data has been corrected as this was deemed the best course of action.

Merge pull request #2 from rjarry/master
test: fix corrupted date header in sample messages

Adds a new function allowing threading based upon a single email that…
… leaves placeholder
noodes in tact. Improves handling of bad References: headers in test and example.

Corrects one minor mistake in transcribing the algorithm to Go - a mi…
…ssing
initialization. This also shows how to use References for threading instead of
subject only, even though with our horribly broken test set, some threads will be
discarded as indecipherable.

Provides a more complete interface for the visualize example and fixes
documentation to match.

Production ready stable interface release

Pre final release release to check that all the documentation etc cor…
…rectly in the various
opensource toolsets that pick up GitHub repos and give us badges etc.

This release contains a breaking change which moves the location of t…
…he package go
files to the top level repo. The open source toolsets don't really get on with
having the pkg directory. Other than that, it is the same as v0.9.0 - you just
need to change your include path. Well, that is, if anyone is acutally using this
software yet.

This is the inital, working, not quite production but very nearly rel…
…ease. There should
be no bugs if the tests are good enough. It is good enough for production, but be aware
that the 1.0.0 release may introduce a few tweaks, such as a generic sort for instance.