settings: Add option to toggle the pointer icon when using stylus

Change-Id: Ib9c22ecb05cc698ead5bfffa34d2a2ffa9c21e13

Conflicts:
	res/values/strings.xml
	src/com/android/settings/inputmethod/InputMethodAndLanguageSettings.java
inputmethod: Fixup remove stylus preference for non stylus devices

This commit included following changes

 * Move show stylus icon checkbox to Pointer Settings Category
 * Fixup issues stylus preference doesn't remove if not supported
 * Improve the code remove stylus preference if not supported
 * Remove an unnecessary variable introduced on http://review.cyanogenmod.org/#/c/33774/

Change-Id: I0f2e1b5cda00033915bb25902ce970f9eda52048

Conflicts:
	src/com/android/settings/inputmethod/InputMethodAndLanguageSettings.java
Fix NPE in Settings -> Language & input -> Default -> Setup input
methods

If the InputMethodAndLanguageSettings fragment is launched in IME-only
mode, it removes most preferences, so we need to null-check them before
use.

Change-Id: I297cc9c6885f62ed6ff65937ef5da401ab7cd271
JIRA:CYAN-896