Add keyHintIcon attribute to BaseKeyboard.Key class

This keyHintIcon attribute is used to specify hint icon drawable at
top right corner of Key.

Change-Id: Icaa91e63c4473b2513396bd3fbeb8ed6fd73586c
diff --git a/java/res/xml/kbd_qwerty.xml b/java/res/xml/kbd_qwerty.xml
index 5e68fd6..ed581a9 100644
--- a/java/res/xml/kbd_qwerty.xml
+++ b/java/res/xml/kbd_qwerty.xml
@@ -28,43 +28,53 @@
     <Row>
         <Key
             latin:keyLabel="q"
+            latin:keyHintIcon="@drawable/keyboard_hint_1"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_q"
             latin:keyEdgeFlags="left" />
         <Key
             latin:keyLabel="w"
+            latin:keyHintIcon="@drawable/keyboard_hint_2"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_w" />
         <Key
             latin:keyLabel="e"
+            latin:keyHintIcon="@drawable/keyboard_hint_3"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_e" />
         <Key
             latin:keyLabel="r"
+            latin:keyHintIcon="@drawable/keyboard_hint_4"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_r" />
         <Key
             latin:keyLabel="t"
+            latin:keyHintIcon="@drawable/keyboard_hint_5"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_t" />
         <Key
             latin:keyLabel="y"
+            latin:keyHintIcon="@drawable/keyboard_hint_6"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_y" />
         <Key
             latin:keyLabel="u"
+            latin:keyHintIcon="@drawable/keyboard_hint_7"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_u" />
         <Key
             latin:keyLabel="i"
+            latin:keyHintIcon="@drawable/keyboard_hint_8"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_i" />
         <Key
             latin:keyLabel="o"
+            latin:keyHintIcon="@drawable/keyboard_hint_9"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_o" />
         <Key
             latin:keyLabel="p"
+            latin:keyHintIcon="@drawable/keyboard_hint_0"
             latin:popupKeyboard="@xml/kbd_popup_template"
             latin:popupCharacters="@string/alternates_for_p"
             latin:keyEdgeFlags="right" />