ENH: Update CTK

$ git shortlog d6171b8..b643fd8 --no-merges
Andras Lasso (1):
BUG: Enable Ctrl-C shortcut in Python console in the history area

Andreas Fetzer (2):
Fixed again duplicate signal connection
Removed redundant call of hideUIDColumns

Csaba Pitner (1):
BUG: Clear box icon renamed to be considered

Julien Finet (1):
Add white border to clear icon

Laurenn Lam (1):
Add setChecked method to ctkButtonGroup

Sascha Zelzer (2):
QAtomicInt does not have a int conversion operator any more.
Fixed deprecated warning with Qt5.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24193 3bd1e089-480b-0410-8dfb-8563597acbee