Add GlowPadView extensions needed for lockscreen targets and nav ring.

Change-Id: Ia4b8adfb4a411b1bc40db600d398f02fceecc828
Fix layout of MultiWaveView and GlowPadView.

If the calculated size of the rings is much smaller than the measured
size (which is happening e.g. on mdpi 600x1024 tablets), the glow pad
appeared shifted to the right.
This happened due to the insets being calculated as difference of
available and needed size, and later on being added to the available
size. Example numbers (Nexus 4 with density forced to 160):
- computed size in onMeasure: 768x505
- scaled size in onMeasure: 505x505
- thus, insets are calculated as 131/0
- in onLayout, placementWidth (364) and max target width (108) are much
  smaller than width (768)
- thus, center is calculated as 131 + (768 / 2) = 515, thus shifted to
  the right

Fix that by not using width in the calculation, as the inset size
already takes it into consideration.

Change-Id: I045c5d523436cc54c5af3429644737c7f83bec59
Custom Navring Targets (1/2)

All credits to cyanogenmod.

Allows up to 3 custom navring targets.

Conflicts:
	core/java/android/provider/Settings.java
	core/res/res/values/pa_symbols.xml
	packages/SystemUI/res/values/pa_strings.xml

PS1: Changed from CM Torch to Omni LightBulb

Conflicts:
	core/java/android/provider/Settings.java
	core/res/res/values/pa_symbols.xml
	packages/SystemUI/res/values/simpleaosp_strings.xml

Conflicts:
	core/java/android/provider/Settings.java
	core/res/res/values/pa_symbols.xml
	packages/SystemUI/res/values/pa_strings.xml