Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

src/qt/apptraits.cpp

@@ -33,7 +33,7 @@ wxTimerImpl *wxGUIAppTraits::CreateTimerImpl(wxTimer *timer)
 // void wxGUIAppTraits::MutexGuiEnter()
 // {
 // }
-// 
+//
 // void wxGUIAppTraits::MutexGuiLeave()
 // {
 // }