Make the Settings side of the date format settings more locale-aware.

Remove the two formats that have a spelled-out month, since applications
using this setting are trying to format numeric dates.

Do not forcibly set the setting the first time you go into Date & Time --
let the setting remain null if it was null before.

Add a choice corresponding to null to the list of format options.  It will
look like "Normal (12-31-2009)" in the list, and will cause the system
to use whatever numeric format the locale calls for.

For the other choices, feed them to the locale-aware formatter so they
will appear with the punctuation that the locale calls for.
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 3b91ef6..d2ca51b 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -243,6 +243,10 @@
     <!-- Do not translate. Used as the value for a setting. -->
     <string name="default_date_format"><xliff:g id="default_date_format">MM/dd/yyyy</xliff:g></string>
 
+    <!-- The option in the date-format picker for using the normal format
+         called for by the user's locale. -->
+    <string name="normal_date_format">Normal (<xliff:g id="date" example="12-31-2009">%s</xliff:g>)</string>
+
     <!-- Label of preview text when tweaking font size -->
     <string name="display_preview_label">Preview:</string>
     <!-- Label for chosen font size -->