Fix crash of date selector.

How to reproduce:
- Open date filter
- Turn off screen
- Turn on screen
- Reopen date filter

Also move around code a bit to follow existing design patterns more
closely.

Change-Id: Ibd46a09db6c5fb4623a1ef8062af971aee0e1a60
Fix display condition for minutes.

Previous display: 2 hours 0 mins
Now displayed: 2 hours

Change-Id: I4f428e2b16063ab285d25c33eb6ebe2c6f769d2e
Fix threads running after entering call log, possibly affecting battery
life.

When having entered the call log or the call stats activities once, the
contact lookup thread (which wakes once per second) continued to run
even after leaving the activity.
The root cause for that was that the ViewTreeObserver obtained at
registerOnPreDrawListener() time was no longer valid when
unregisterOnPreDrawListener() was called. Fix that by storing a
reference to the observed view instead of the observer and fetching the
current observer when needed.

Change-Id: I3209712a52371f99772f522d03bc6b209272089c
Allow quick pre-selection of filter range.

Change-Id: I13bacaffdff21d8feb60a9c8939d3e17057a60f8

Conflicts:

	res/values-de/strings.xml
huh?