Simplified alpha listview animation

most of these animations look like garbage.. so lets
just include a simple alpha one without interpolation
because it is not needed.

PS2: some cleanup and fix potential null pointer
PS3: small tweak to speed up alpha animation.. may tweak
transparency levels next..

TO DO: make it dependent on the values set in developer settings

Change-Id: I79c184e9125689fa88d0b2cf160e420517f3a91c

Conflicts:
	core/java/android/provider/Settings.java
	core/java/android/widget/AbsListView.java
frameworks: Animation control

Allows setting of some system animations based on AOKP's custom
system animations by stevie spear and listview animations plus some
extra stuff.

-Vanir

Change-Id: Id360abe158d36ab85c1c0d0103428d4a8867e70c

Conflicts:
	core/java/android/provider/Settings.java
	core/java/android/widget/AbsListView.java
	core/res/res/values/strings.xml
	core/res/res/values/symbols.xml