Add more readable command-line flags for sbt testing framework

[olafurpg]

Currently, the command-line flags for the MUnit sbt testing framework implementation are mostly undocumented (no overview of all available flags) and they're pretty cryptic (mostly single character flags). We should revamp the command-line parser to support new flag names that are more self-documenting while keeping compatibility with the old flag names (which we may want to deprecate).