Dictionary changes: GNOME Data Access 5 manual

## Dictionary changes

The GdaDict object has been removed and the GdaMetaStore object introduced to replace it, but with slightly different features.

The GdaDict object used an XML file to store its data which imposed parsing potentially big XML files and creating its own internal structures from it (before discarding the XML tree) which was both CPU and memory intensive. Memory was also wasted as most of the time not all the dictionary would be exploited. The new GdaMetaStore object relies on a database (an SQLite file by default) to store its data which solves the problems mentioned above.

It was difficult for applications to add their own data in the dictionary (the API existed but was difficult to understand and use), this has been solved by allowing applications to create DBMS objects into the GdaMetaStore's associated database.

There was a strange relation between a GdaDict object and a GdaConnection object as a connection needed to be assigned to a GdaDict object; this is not the case as now each GdaConnection object builts a GdaMetaStore when it needs it (providers implementations may benefit from it) and the user can provide his own GdaMetaStore object when needed.