StatusBar: Homogenize and slightly reduce icons margins
Improve notification shade collapse code.

- Collapse after dismissing the last notification
- Avoid duplicate code paths for collapsing
- Improve variable naming according to AOSP review suggestions

Change-Id: Ic6f26a61f263c5beebbcc9725fe8914d3858576f

Conflicts:

	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
Allow adjusting progress on touch events.

Change-Id: Ide0a7ae057a62f3631a32eeaa63f3e04dec5bf54
Prefer artist over album artist.

E.g. when playing a compilation title, one very likely wants to see the real
artist instead of 'Various artists'.

Change-Id: Ie200f2f8b0b90d3470c2e2e4ca6f91f9b117fb1f