[FIX] fixed regression due to 9ccedf2

    when catching CTRL-F in table explorer, other key presses where not
    relayed, so cursor navigation in table explorer did not work any
    more
[FEATURE] emzed.console now in q4thread mode

    started IPython shell now starts with PyQt4 background thread,
    so opening and closing a sequence of Qt windows does not crash
    the shell any more.