PC Facade Improvements: argument handling, exception logging, using AutoCloseable engine

* Wrapped launch arguments handling and exception logging into their own methods. 
* Now taking advantage of the AutoCloseable interface implemented by the TerasologyEngine class, resulting in a more compact main method and a full handling/logging of all exception-triggering paths.

These changes had been originally discussed in PR #1108 and are the last potential changes to the PC Facade from that PR.
@Cervator That's correct. I guess it makes sense to check both with an `or` operator so that CR will not show if either of the two flags is set. Some Javadoc could be useful to explain that :smile: