Allow creating custom dialogs in DialogPreference.

This allows creating non-AlertDialogs while still using the click and
state handling of DialogPreference.

Change-Id: I54fd7d6d6b9f6a49fef1ae95e0178838b3edfa56
Factor out preference-in-storage check to overridable method.

Change-Id: I2fff3192802f8a180330fda66388eda394334a5a
Treat default value that wasn't found as empty value.

Fixes http://code.google.com/p/android/issues/detail?id=33220

Change-Id: If22e8b245f688d922c168aa54c8acf743c0644d7
Fix certain setting writes being incorrectly skipped.

If a value that previously had a very long value (over the 500 char
threshold) is now set to null, isRedundantSetValue would incorrectly
return true even though the value was changed.

Change-Id: Ia5304743024ec01024be98aa51ed260d38caf93c
Allow adjusting progress on touch events.

Change-Id: Ide0a7ae057a62f3631a32eeaa63f3e04dec5bf54

Conflicts:
	core/java/android/widget/AbsSeekBar.java