[bugs, changelog] update.
[qt4] prepolishstarted is not used anymore in qt4
[qt5] event will not be NULL...
[qt] shadow helper cleanup
[qt] noEtch in qtc props
[math] clean up
[qt4/shadow] fix lancelot
[qt] QBalloonTip shadow
[misc] next version is 1.8.18
[qt] wrong side for QBalloonTip....., read the source code wrong.... Thanks to Hugo...
[qt5] try the second version of prePolishing in Qt5
[qt5] fix menu background for mdi sub window
[qt] prepolish clean up
[qt5] split prepolish
[qt] more pre polishing
[qt] base style clean up
[qt] version clean up
[qt] sync qtcurve.h
[qt] for loop
[qt5] more for loop