Add :vsplit and :split support in kdevelop
Summary: Using :vsplit and :split to split the view as in vim is something that could be nice.
Test Plan: Run :vsplit the screen should get split into two new screen
Reviewers: brauch, mwolff, KDevelop
Reviewed By: mwolff
Subscribers: flherne, tcanabrava, mwolff, kdevelop-devel
Differential Revision: https://phabricator.kde.org/D4250