SQLite3Store now uses buffers. Klio-store now allows the sensor description to be informed. Several other improvements.
Performance improvements in Stores.
Minor improvement in MSGStore test.
Minor improvement in unit tests.
Some methods of the Store class are now virtual.
Method Store.get_sensors_by_external_id() has been improved.
The zSql parameter is no longer used by sqlite3_prepare_v2().
Merge branch 'ew-dev' into development