Columns moved pa package vindur.column

Signed-off-by: Sergey Krivohatskiy <s.krivohatskiy@gmail.com>
document package created. Some classes moved to this package. New engine test added

Signed-off-by: Sergey Krivohatskiy <s.krivohatskiy@gmail.com>
Columns refactored

Signed-off-by: Sergey Krivohatskiy <s.krivohatskiy@gmail.com>
Dublicate code moved to BitSetUtils class. Columns refactored

Signed-off-by: Sergey Krivohatskiy <s.krivohatskiy@gmail.com>