Summary: So that it can be integrated in QtQuick applications

Test Plan: Implemented it Discover, everything seems to work

Reviewers: vkrause

Reviewed By: vkrause

Differential Revision: https://phabricator.kde.org/D5960

This will be useful for the visualization.

Necessary to eventually support hierarchical category aggregation here.

This makes it easier to use this code embedded into another codebase.

Move the unstructured vendor-specific information to its own element, so
we can properly categorize the OpenGL version.

A small step towards a proper QML API.

This enables us to have two user roles: people with read-only access to
data for viewing/analyzing it, and people with full write access to
manage products and survey campaigns.

Will probably need some more pre-processing of the data we get from the
GL driver, it contains some unstructured and/or too specific information
for our purpose.

Same concept and data format as the property ratio source, just monitoring
a QItemSelectionModel instead.

Acked by Volker over IRC

Also, generate camel-case headers while we are at it.

This allows us to test if the cmake config files and headers are actually
usable when installed too.

This requires a few adjustments to keep things building with Qt4, the
latest version of the pri file generator explicitly depends on Qt5 now.

Reviewers: vkrause

Reviewed By: vkrause

Differential Revision: https://phabricator.kde.org/D5578

Preparing for moving this to a shared config file with the CLI tool.

QSettings requires an organization name there to work correctly.