Update database and some smaller changes/fixes

-Updated flybook.db
-Updated DBConstants.java
-Removed column prefixes and modified more code to use DBConstants
-Comment problematic code in FlightsTable.java
-Changed FlightEntriesFSDelegate.getQueryStatement(..) to not use alias
for FligthEntries in sql statement, because it causes problems with
filters.
-Renamed FlightEntry to FlightItem (wrapper class)
-FlightsContainer now encapsulates SQLContainer not extend it