Customizable lockscreen & navring targets (1/2)

Ported from OmniROM

OmniROM commit:
https://github.com/omnirom/android_frameworks_base/commit/69aee5c343b0b1d8721b9d25ef37cb44ad3303f4

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This is a squashed commit, ported from CM:

Add GlowPadView extensions needed for lockscreen targets and nav ring
Author: Danny Baumann <dannybaumann@web.de>
Change-Id: I4f82fd3fe04ac16c6737d38b2473f2a533c5d326

Framework : Lockscreen - Customizable shortcuts
Author: Danesh M <daneshm90@gmail.com>
Change-Id: Ic3b935df5c0da35f31373d96943e442dc39cf11b

Add back navigation ring customization
Author: Danny Baumann <dannybaumann@web.de>
Change-Id: Iebe4ec7c2519b85cfd5189d060444764a50f3cf6

Conflicts:
	core/java/android/provider/Settings.java
	core/java/com/android/internal/widget/multiwaveview/GlowPadView.java
	core/res/res/values/symbols.xml
	packages/Keyguard/src/com/android/keyguard/KeyguardSelectorView.java