It was hard-coded in TerminalDisplay.cpp - Shift+Up always results in
ScrollLineUpCommand regardless of settings in *.keytab. Now those
commands are correctly parsed by KeyboardTranslator.
Fixeslxde/qterminal#348
This fix is similar to KDE/konsole@b88dfb402a
while I use signals and slots instead of introducing new pointers. That
sounds more reliable :)