Getting an image from mysql database (as BLOB field) through subclassed QSqlQueryMode

[anda_skoa]

Couple of things:

- in order to be able to use this class as a QQuickImageProvider, it needs to have a "is-a" relation ship, i.e. publically inherit from QQuickImageProvider
- in data() it doesn't make sense to use the role as given to query the base class, after all these roles will most often be your custom roles and have no meaning for the base class
- you are missing the roleNames() override that returns the mapping of role names (used in QML) to role numbers (using in the C++ API).

Cheers,
_