Add Stylus gestures features (2/2) from CM 10.1

https://github.com/cyanogenmod/android_packages_apps_Settings/commit/283a1d351f90a194e980d29fff8f97fb3e8fcc2c#diff-4
also add :
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/
https://github.com/CyanogenMod/android_packages_apps_Settings/commit/de0b076e849e7a3f0e57ab3ff6fe5f2128dd5087

Change-Id: Ie84e8b6c0038fee380b320f80eeeacc5c203d433