Move the shortcut management in the settings object
Summary:
This uses the new KPropertySkeletonItem facility to allow proper
integration with KGlobalAccel while keeping all the nice semantic coming
from KConfigXT.
This required turning the kconfig_compiler code into a base class and
inheriting from it to introduce the property managed via
KPropertySkeletonItem.
Reviewers: Plasma, davidedmundson, bport, crossi
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D25212