macOS, tvOS, watchOS and Swift Package Manager support

Support multiple platforms + Swift Package Manager (#3)

* Reorganise folders for SPM support and multiple platforms

* Default associated type for cleaner conformances

* Update readme

* Update readme

* Run CI on multiple platforms

* test

* Test

* Fix linux tests

* Restore all travis builds

* Fix pod warnings

Swift 4 support

1.1.0

Installation steps

First release

New API - State machine with inputs and local state (#1)

* Breaking: Model states using protocol allowing for local data + inputs

* DSL

* Side effect variations

* Simple specs

* Reorganise

* Specs

* Version 1.0.0

* Travis

* Script

* Equality

* Implement AnyState

* Fix Ci