Replace open() & close() with failable init() + deinit

[beltex]

• Would make things simpler and cleaner
• However, still a bit confused on deinit's behaviour
  • It's only called once the object is nil (no refs). Don't want to have to manually set it once done (might as well use close()). Neither do we want to use optional binding (it's a long lived object, gets repetitive). Want to use an implicitly unwrapped optional (due to the failable init()), but then deinit doesn't get called
  • What happens on program exit? Doesn't seem to be called. Want to still make sure that connection is closed. It's not a memory issue, OS X takes care of that on proc exit

[beltex]

This no longer applies since SMC is now a struct, not a class. Even so, the general conclusion was that deinit() should not be relied on for such things. The Swift book seems to suggest it can nonetheless. If a new development comes along, we can look at this again. But it probably wouldn't be worth the performance trade-off anyway.