Add support for fallback keycodes.

This change enables the framework to synthesize key events to implement
default behavior when an application does not handle a key.
For example, this change enables numeric keypad keys to perform
their associated special function when numlock is off.

The application is informed that it is processing a fallback keypress
so it can choose to ignore it.

Added a new keycode for switching applications.

Added ALT key deadkeys.

New default key mappings:
- ESC -> BACK
- Meta+ESC -> HOME
- Alt+ESC -> MENU
- Meta+Space -> SEARCH
- Meta+Tab -> APP_SWITCH

Fixed some comments.
Fixed some tests.

Change-Id: Id7f3b6645f3a350275e624547822f72652f3defe
diff --git a/include/ui/InputReader.h b/include/ui/InputReader.h
index 8ec5421..b466ff1 100644
--- a/include/ui/InputReader.h
+++ b/include/ui/InputReader.h
@@ -402,7 +402,6 @@
     } mLocked;
 
     void initializeLocked();
-    void initializeLedStateLocked(LockedState::LedState& ledState, int32_t led);
 
     void configureParameters();
     void dumpParameters(String8& dump);
@@ -414,6 +413,8 @@
 
     ssize_t findKeyDownLocked(int32_t scanCode);
 
+    void resetLedStateLocked();
+    void initializeLedStateLocked(LockedState::LedState& ledState, int32_t led);
     void updateLedStateLocked(bool reset);
     void updateLedStateForModifierLocked(LockedState::LedState& ledState, int32_t led,
             int32_t modifier, bool reset);