Allow the user to save as files with different extensions.

There is still an open issue in this fix since the new extension might be of a different mime type (and our editors are attached to it currently).
More details documented in the code.

Task-number: QTCREATORBUG-2094
Reviewed-by: Thorbjorn Lindeijer

src/plugins/coreplugin/coreconstants.h

@@ -246,6 +246,8 @@ const char * const SETTINGS_CATEGORY_CORE_ICON = ":/core/images/category_core.pn
 const char * const SETTINGS_TR_CATEGORY_CORE = QT_TRANSLATE_NOOP("Core", "Environment");
 const char * const SETTINGS_ID_ENVIRONMENT = "A.General";
 
+const char * const ALL_FILES_FILTER      = QT_TRANSLATE_NOOP("Core", "All Files (*)");
+
 const int TARGET_ICON_SIZE = 32;
 
 } // namespace Constants