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/process.h

@@ -15,7 +15,7 @@
     notified about the process termination and also retrieve its exit status which is
     unavailable from ::wxExecute() in the case of asynchronous execution.
 
-    @note 
+    @note
         If the @c wxEVT_END_PROCESS event sent after termination is processed by the
         parent, then it is responsible for deleting the wxProcess object which sent it.
         However, if it is not processed, the object will <b>delete itself</b> and so the
@@ -110,17 +110,17 @@ public:
     /**
         Detaches this event handler from the parent specified in the constructor
         (see wxEvtHandler::Unlink() for a similar but not identical function).
-    
+
         Normally, a wxProcess object is deleted by its parent when it receives the
-        notification about the process termination. 
-        
-        However, it might happen that the parent object is destroyed before the external 
-        process is terminated (e.g. a window from which this external process was launched 
-        is closed by the user) and in this case it @b should not delete the wxProcess 
-        object, but @b should call Detach() instead. 
-        
-        After the wxProcess object is detached from its parent, no notification events 
-        will be sent to the parent and the object will delete itself upon reception of 
+        notification about the process termination.
+
+        However, it might happen that the parent object is destroyed before the external
+        process is terminated (e.g. a window from which this external process was launched
+        is closed by the user) and in this case it @b should not delete the wxProcess
+        object, but @b should call Detach() instead.
+
+        After the wxProcess object is detached from its parent, no notification events
+        will be sent to the parent and the object will delete itself upon reception of
         the process termination notification.
     */
     void Detach();
@@ -211,7 +211,7 @@ public:
     /**
         It is called when the process with the pid @a pid finishes.
         It raises a wxWidgets event when it isn't overridden.
-        
+
         Note that this function won't be called if you Kill() the process.
 
         @param pid