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/textwrapper.h

@@ -19,7 +19,7 @@
 
     Here is an example function using this class which inserts hard line breaks
     into a string of text at the positions where it would be wrapped:
-    
+
     @code
     wxString WrapText(wxWindow *win, const wxString& text, int widthMax)
     {