[HotFix[ Revert Progressive Loading (Commit 594a18c652)

Commit https://github.com/alterm4nn/ChronoZoom/commit/594a18c652e95390d6fd3de3d89b6a81a56d9a43 needs to be reverted since Database migration failed with error: 

ALTER TABLE ALTER COLUMN ForkNode failed because one or more objects access this column.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)