Initial cleanup of the Todo-plugin.

- Compile with QT_NO_CAST_FROM_ASCII, fix
  single character strings
- Remove special character from constants.h,
  fix constant names
- Fix tr() errors.
- Clean include directives
- struct -> class (coding style)

Change-Id: Id6108a03312bdecc6df3015b5a12653c95390647
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

src/plugins/todo/todoitemsmodel.cpp

@@ -34,6 +34,8 @@
 #include "todoitemsmodel.h"
 #include "constants.h"
 
+#include <QIcon>
+
 namespace Todo {
 namespace Internal {
 
@@ -117,7 +119,7 @@ QVariant TodoItemsModel::headerData(int section, Qt::Orientation orientation, in
 
     switch (section) {
         case Constants::OUTPUT_COLUMN_TEXT:
-            return tr(Constants::OUPTUT_COLUMN_TEXT_TITLE);
+            return tr(Constants::OUTPUT_COLUMN_TEXT_TITLE);
 
         case Constants::OUTPUT_COLUMN_FILE:
             return tr(Constants::OUTPUT_COLUMN_FILE_TITLE);