Recognize X-KDE-FormFactor as stringlist

Review Request #124066 - Created June 11, 2015 and submitted - Latest diff uploaded

Sebastian Kügler
arichardson, dfaure

This patch adds X-KDE-FormFactor to the keys recognized as stringlists.

We would like to see this to go in to allow us to filter plugins (KCMs for example) by form factor, so we only display UI plugins that are suitable for a given target device.

The idea is that plugins indicate which form factor (for example media center, tablet, desktop, etc...) they're suitable for, and the "host application" filters based on these.

If this approach is deemed valid, I'd be happy to add convenience API to KPluginMetaData, i.e. QStringList KPluginMetaData::formFactor(). This patch would be the minimal implementation we'd need.

The naming of the key is of course open to better suggestions.

added autotest, also implemented using this in the Plasma Active settings app as proof-of-concept, works like a charm.