Support 9-patch drawable for spacebar icon

java/res/drawable-hdpi/sym_keyboard_spacebar_lxx_dark.9.png

java/res/drawable-mdpi/sym_keyboard_spacebar_lxx_dark.9.png

java/res/drawable-xhdpi/sym_keyboard_spacebar_lxx_dark.9.png

.../res/drawable-xxhdpi/sym_keyboard_spacebar_lxx_dark.9.png

java/res/values/attrs.xml

java/res/values/keyboard-icons-lxx.xml

java/res/values/themes-lxx.xml

java/res/xml-sw600dp/key_styles_common.xml

java/res/xml/key_styles_common.xml

java/res/xml/key_styles_number.xml

java/src/com/android/inputmethod/keyboard/Key.java

java/src/com/android/inputmethod/keyboard/KeyboardView.java

...rc/com/android/inputmethod/keyboard/MainKeyboardView.java