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/publicity/WoWoW30.html

@@ -170,7 +170,7 @@ class, container classes, as well as classes for threading,
 networking, XML parsing, path and configuration management, logging,
 debugging etc. These functions and classes have been separated into
 their own library both for being able to write non-GUI apps as well
-as to make maintainance easier through reduced interdependence. 
+as to make maintainance easier through reduced interdependence.
 </P>
 <P ALIGN=JUSTIFY>Many of the changes to wxString and the container
 classes are located in wxBase, but on top of that support to wxBase
@@ -186,7 +186,7 @@ change. Rather, this paragraph summarizes the most relevant changes
 to the GUI classes of wxWidgets. Given wxWidgets' nature as a GUI
 library, these changes are also most likely to be visible to the user
 and may thus be the most important changes from a user's perspective
-(although not necessarily from a developer's perspective): 
+(although not necessarily from a developer's perspective):
 </P>
 <UL>
 	<LI><P ALIGN=JUSTIFY>wxDataViewCtrl and wxDataViewTreeCtrl: this
@@ -310,7 +310,7 @@ cases, supporting an old version of GTK+ hinders development so we
 decided to declare GTK+ 2.6 the minimum toolkit version that is
 supported. As an example, this made it possible to always use the
 GTK+ file dialog instead of the old generic file dialog which had to
-be used when GTK+ didn't have a usable file dialog. 
+be used when GTK+ didn't have a usable file dialog.
 </P>
 <P ALIGN=JUSTIFY STYLE="margin-bottom: 0cm">Other parts of wxGTK that
 were rewritten or which underwent a major update include, but are not