Code cleanups

Summary:
Send options as an Array

*should* be faster as potentially there will be just one allocation

Rename variable: QApplication qa to app.

qa means nothing and the default for Qt apps is to have the
QApplication var named app.

Return directly without creating temporaries

Extract logic from main function

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D22323