Added: Writing linkto events to the projection -order stream to allow ordered
recovery.  Currently writing for all sources, but we should only write this
stream for multi-stream sources
Added: MultiStreamMultiOutputCheckpointManager.cs - no recovery support and
tests yet
Changed: CheckpointLoaded message replaces with two messages: CheckpointLoaded
and PrerecordedEventsLoaed. CoreProjection StateLoadedSubscribed state replaced
with two states: StateLoaed and Subscribed.  Tests updated accordingly. Added
base test fixture for multi-stream checkpoint manager tests
Added: projection subscription ID to filter out messages from already dropped subscriptions

(more reliable that sequence no)
Added: reading and dispatching pre-recorded events on recovery
Merge branch 'dev' into projections-ordering
Merge branch 'dev' into projections-ordering
Merge branch 'dev' into projections-ordering
Fixed: subscriptionId management; handling events while not running; enabled
indexed events for partitioned projections;
Merge branch 'dev' into projections-ordering
Fixed: multi stream event ordering when reading via event index
Error messsage fixed
Merge branch 'projections-ordering' into dev
Merge branch 'dev' of github.com:EventStore/EventStore into dev