Back to previous keyboard layout by canceling sliding input

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

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

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

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

.../android/inputmethod/keyboard/internal/KeyboardState.java

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

...thod/keyboard/internal/KeyboardStateSingleTouchTests.java

...inputmethod/keyboard/internal/KeyboardStateTestsBase.java

...d/inputmethod/keyboard/internal/MockKeyboardSwitcher.java