[Qgis-developer] QtXml is no longer maintained in Qt5

[Even Rouault]

> Considering a sponsor: it might be packaged in a proposal of a native
> project file format that also supports storing layers. 

You could potentially consider using a GeoPackage container as a base for that 
:
- http://www.geopackage.org/spec/
- http://www.gdal.org/drv_geopackage.html

It would cover storing vector layers. The QGIS specific parts could be stored 
in extension tables.

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