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/validate.h

@@ -81,7 +81,7 @@ public:
        Returns if the error sound is currently disabled.
     */
     static bool IsSilent();
-    
+
     /**
         Associates a window with the validator.