Added db.DatabaseException
Database: Now throws DatabaseExceptions instead of RuntimeExceptions
Added Database.queryInt
Added Database.lockWrite(table) and Database.unlock()
Vehicles: Added create() and delete()
Vehicles.create: try/finally on lock to ensure it never fails to unlock
VehicleLogic: Implemented new/delete
Merge branch 'DatabaseException' into VehicleNewDelete
Database.LockWrite was not a good strategy, trying something else
Database: Added query(conn,sql) and update(conn,sql)
Vehicles: locking create() working
Database: trivial
Vehicles: Create works, but problematic in VehicleLogic
Added Database.queryString
VehicleLogic: Now working correctly.  But ugly.
Database: Replaced typed funcs with querySingle and queryArray generics
Database: swapped generics' parameter order
DatabaseConstraints: Updated to use generics
Commented out outdated test code
Revert "DatabaseConstraints: Updated to use generics"

This reverts commit dc238742c53758b57317e4c925473c2df3fbf840.