Add more const-ness to the stream endpoint/pipe functions where possible.

Projects/LEDNotifier/Doxygen.conf

@@ -615,7 +615,10 @@ RECURSIVE              = YES
 # excluded from the INPUT source files. This way you can easily exclude a
 # subdirectory from a directory tree whose root is specified with the INPUT tag.
 
-EXCLUDE                = Documentation/ CPUUsageApp/ HotmailNotifierApp/ LEDMixerApp/
+EXCLUDE                = Documentation/       \
+                         CPUUsageApp/         \
+                         HotmailNotifierApp/  \
+                         LEDMixerApp/
 
 # The EXCLUDE_SYMLINKS tag can be used select whether or not files or
 # directories that are symbolic links (a Unix filesystem feature) are excluded