Generate KeyboardLabelsSet from donottranslate-more-keys.xml

This change introduces makelabel tool that reads all languages'
donottranslate-more-keys and generate KeyboardLabelsSet.java source
file. The makelabel command must be invoked prior to compile LatinIME.

Change-Id: I7515c7919c535e30f9c80a37bdc831d0f682cd43
diff --git a/java/res/xml-sw600dp/rowkeys_symbols2.xml b/java/res/xml-sw600dp/rowkeys_symbols2.xml
index e0121a3..fd77416 100644
--- a/java/res/xml-sw600dp/rowkeys_symbols2.xml
+++ b/java/res/xml-sw600dp/rowkeys_symbols2.xml
@@ -26,13 +26,13 @@
     <Key
         latin:keyStyle="currencyKeyStyle" />
     <Key
-        latin:keyLabel="@string/keylabel_for_symbols_percent"
-        latin:moreKeys="@string/more_keys_for_symbols_percent" />
+        latin:keyLabel="!label/keylabel_for_symbols_percent"
+        latin:moreKeys="!label/more_keys_for_symbols_percent" />
     <Key
         latin:keyLabel="&amp;" />
     <Key
         latin:keyLabel="*"
-        latin:moreKeys="@string/more_keys_for_star" />
+        latin:moreKeys="!label/more_keys_for_star" />
     <!-- U+2013: "–" EN DASH
          U+2014: "—" EM DASH -->
     <Key
@@ -40,7 +40,7 @@
         latin:moreKeys="_,&#x2013;,&#x2014;" />
     <Key
         latin:keyLabel="+"
-        latin:moreKeys="@string/more_keys_for_plus" />
+        latin:moreKeys="!label/more_keys_for_plus" />
     <include
         latin:keyboardLayout="@xml/keys_parentheses" />
 </merge>