Added graphics system. Need to archetect how systems and entities will interact.
Using flowchart to work out how engine components will interact.
Working on clarifing how each system acts in relation to time to try and ensure deterministic behavior.

- Working to ensure that update order of components/objects inside of systems do not matter,
  since they will not be ordered in any meaningful way with respect to time.
Iterated on time flow and added flow of events.

- Not sure if component level events should exist.
Further work on defining order of events.
Merge branch 'unstable' of https://github.com/peter-clark/lifeline into unstable