Cancel gesture typing by sliding out from keyboard

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

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

.../android/inputmethod/keyboard/internal/GestureStroke.java

...hod/keyboard/internal/GestureStrokeWithPreviewPoints.java

...id/inputmethod/keyboard/internal/PointerTrackerQueue.java

...roid/inputmethod/keyboard/internal/PreviewPlacerView.java

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

...putmethod/keyboard/internal/PointerTrackerQueueTests.java