Prepare for next dev iteration.
Refactor events:

* Get rid of misleading inheritance hierarchy.
Rather than grouping unrelated (inheritance-wise) classes as static
inner classes of a parent type
(e.g. BuildSyncPlan:(Start|ProgressChanged|Finished)), this moves them
all into a common events class. There's still no inheritance hierarchy
for related tasks as they all derive from TaskEvent, but at least
that's now clear.

* Low/Mid/High level events now implement marker
interfaces to allow filtering by level.

* Stop using public final properties for easier mocking.
General cleanup and fix bunch of inspector warnings.
Fix bug where config file parameter ignored if first parameter.
Speed up playlist generation by spepcifying length as indeterminate. #6
Prepare for release.