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/wrapsizer.h

@@ -58,7 +58,7 @@ public:
     */
     virtual bool InformFirstDirection(int direction, int size,
                                       int availableOtherDir);
-    
+
     virtual void RecalcSizes();
     virtual wxSize CalcMin();