decrease StateData space by more than 50% and half the number of needed mallocs
Summary: less space used by the object itself and only one vector instead of two => half of the needed allocations
Test Plan: make && make test
Reviewers: vkrause, dhaumann
Reviewed By: dhaumann
Subscribers: kwrite-devel, kde-frameworks-devel
Tags: Kate, Frameworks
Differential Revision: https://phabricator.kde.org/D15134