[Qgis-developer] Update to the SpatiaLite provider

[Giuseppe Sucameli]

Hi devs, hi all,

Alessandro Furieri has sent to me a patch to support the features
available from the newest SpatiaLite v4 into the provider, mostly
the intensive use of statistics to improve performaces.

@Alessandro: please, could you tell us what's new in
the provider? I know some details, but I'm sure devs would
like to know more.

The patch doesn't break API, but could break the provider
functionalities (worst). Alessandro and I have tested it and
everything seems to work fine.

Before merging it I've opened a pull request [1], further tests
are welcome.

Regards.

[1] https://github.com/qgis/Quantum-GIS/pull/346

-- 
Giuseppe Sucameli - Faunalia