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.

docs/doxygen/mainpages/const_stdevtid.h

@@ -29,7 +29,7 @@ identifiers are all in the range between @c wxID_LOWEST and
 @c wxID_HIGHEST and, accordingly, the user code should avoid defining its
 own constants in this range (e.g. by using wxNewId()).
 
-Refer to @ref page_stockitems "the list of stock items" for the subset of standard IDs 
+Refer to @ref page_stockitems "the list of stock items" for the subset of standard IDs
 which are stock IDs as well.
 
 */

docs/doxygen/mainpages/copyright.h

@@ -103,7 +103,7 @@ without express or implied warranty.
 @verbinclude "lgpl.txt"
 
 @page page_copyright_xserver The Open Group and DEC License
- 
+
 @verbinclude "xserver.txt"
 
 */

docs/doxygen/mainpages/samples.h

@@ -914,7 +914,7 @@ control.
 
 The wxWebView sample demonstarates the various capabilities of the wxWebView
 control. It is set up as a simple single window web browser, but with support
-for many of the more complex wxWebView features, including browsing through 
+for many of the more complex wxWebView features, including browsing through
 archives.
 
 @sampledir{webview}