Add support for Attica tags support
This introduces filtering which is applied onto any entry
before handing it to the framework user. Filters can be
set either via knsrc files, or through the Engine API. A
default filter is set to ensure that if the server
suggests certain items should not be shown, those entries
will be hidden from the user (this is already supported
by the KDE Store, and this ensures we support that in
our client side).
It further adds a test tool to more easily perform testing
on KNewStuff's functionality (originally based on the old
knewstuff2 tester, but now with more functionality, and
better visual feedback).
Finally, this fixes a binary compatibility issue caused
by the original version of this commit, see