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.

include/wx/colour.h

@@ -118,7 +118,7 @@ public:
     virtual ChannelType Blue() const = 0;
     virtual ChannelType Alpha() const
         { return wxALPHA_OPAQUE ; }
-    
+
     virtual bool IsSolid() const
         { return true; }