Among other things,
* fix turtle icons size (20x14 -> 16x16)
* use QIcon states instead of changing the turtle icon ourselves each
time (unchecked - off, checked - on)
* make speed limit action in tray menu checkable
* simplify status bar buttons drawing and use QToolButton instead of
QPushButton
Make squeeze labels (used for values on Information tab) display tooltip
on hover if their text doesn't fit. Make selective labels (same as in
GTK+ client) text selectable with keyboard in addition to mouse.
Prevent dialog width growth occured before to fit long error texts.
Mike Gelfand