Remain in previous state while sliding off from shift key

.../android/inputmethod/keyboard/KeyboardActionListener.java

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

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

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

java/src/com/android/inputmethod/latin/LatinIME.java