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.

interface/wx/timer.h

@@ -154,7 +154,7 @@ public:
    @class wxTimerRunner
 
    Starts the timer in its ctor, stops in the dtor.
-*/ 
+*/
 class wxTimerRunner
 {
 public: