New reservations class (Not stable)
New functions in sample_usage page
Fixed GetFlightWithIndex retrieving from the wrong field
Fixed reservation_code field to VARCHAR(8) to fir crc322 hashes
Fixed Statement constructor throwing when some queries are not suppose to return any result
Fixed Statement::GetRow() wrong error detection
Fixed Statement destructor freeing results when there is none.
Changed functions that return NULL to functions that throw exceptions
Changed departure and arrival year of all flights