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/fontpicker.h

@@ -59,7 +59,7 @@ class wxFontPickerCtrl : public wxPickerBase
 {
 public:
     wxFontPickerCtrl();
-    
+
     /**
         Initializes the object and calls Create() with
         all the parameters.