Last before SPM

This is the current state of the master branch as at v0.2.1 which is a major refactor.

Refactor and redesign

The Machinus class now conforms to Publisher so that it can be used as a source of events for Combine.
Redesigned the public API for ease of use.

Re-working background state

Reworked the background state so that it only runs its own actions when transitioning. This allows actions on other states to avoid having to account for a background transition.

Doco refactor

Merge pull request #4 from drekka/develop

Tweaking final and updating doco

Swift 5.0

0.1.0

Swift 5.0

Swift 4.2

0.0.4

Final and background states.