Fixed all but one unittests in Krita

Now all the unittests in folders ./image/ ./ui/ and ./plugins/ pass
on my machine. The only exception is krita-fileformat-kis_exr_test, but
it probably related to the fact that I don't have all the needed libraries
installed.

Good news: now KisSelectionManagerTest and KisZoomAndPanTest do not take
30+ min to execute. The delay was related to the overfilled Qt event queue,
and now they take 90 and 40 sec correspondingly.

CCMAIL:kimageshop@kde.org