If any shift state variants of alphabet keyboard layout is not
specified in KeyboardSet.Element, it will be automatically generated
from base alphabet keyboard definition.

This change also
  * Eliminates KeyboardShiftState object from Keyboard.
  * Removes various set shift state methods from Keyboard.
  * Removes KeyboardSet.Element.elementAutoGenerate attribute.
  * Separates "sticky" Key.backgroundType to "stickyOff" and "stickyOn"
  * Add preserveCase flag to smiley, .com, and labeled special keys.
  * Rename KeyboardShiftState class to AlphabetShiftState.
  * Rename some attributes from *UppercaseLetter* to *ShiftedLetterHint*.
  * Introduce shiftedLetterActivated to Key.keyLabelFlags

Change-Id: I01a0a8efeeaa76820ae728a5bdfa8d02b6ce74b7