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/gdicmn.h

@@ -557,7 +557,7 @@ public:
      */
     void SetBottomLeft(const wxPoint &p);
 
-    
+
     //@{
     /**
         Modifies the rectangle to contain the bounding box of this rectangle