Make getCurrent method of instance classes public

Make getCurrent method of instance classes public thereby making it easier to query the current state.

Align version numbers

v6.0.0-beta.4

Align github and npm version numbers

Customisable logging

Enable custom logging through code such as:

state.setLogger({
	log: () => {},
	error: (message) => console.error(`ERROR: ${message}`) 
});

Reinstate console logging

This version of the beta reinstates logging to the console; a future version will create customisable logging.

Fix package.json

v6.0.0-beta.1

Find a semver for beta 1 that npm is happy with

Fix package.json

v6.0.0-beta+1

Update beta version

Beta release of v6

This is the first beta of the v6 code; it works under node, but has not yet been packaged for web use.