implemented new block system

Fixes recurring design issue that the Blocks were a frequent exception to the
DAG concept. The Blocks connecting to each others inputs/outputs while not
necessarily being "dependent" on each other to produce an image continually
causes issues while trying to create a rendering code path. This redesign
should provide a more "directed" approach to the directed acyclic graph.

app/widget/timelinewidget/view/timelineviewblockitem.cpp

@@ -118,7 +118,7 @@ void TimelineViewBlockItem::paint(QPainter *painter, const QStyleOptionGraphicsI
       painter->fillRect(rect(), Qt::white);
     }
     break;
-  case Block::kEnd:
+  case Block::kTrack:
     break;
   }
 }