libQtCassandra 0.4.6 改进记录：
- This release added direct support for QUuid as row and column keys, and for char * and wchar_t *, removing the need to first cast strings to QString everywhere.
- A bug with testing the row key size to limit of 64535 instead of 65535 was fixed.
- A test for empty row and column keys was added.
- These will now throw an error immediately.
- The documentation was updated accordingly and enhanced