Preparation for animations if Timer and Stopwatch

Converted CircleButtonsLinearLayout to FrameLayout and renamed
CircleTimerView: always draw circle in view center
CountingTimerView: remeasure text size if view's size changed
StopwatchFragment: some lint cleanup
in the layouts:
remove unneeded layout id and attributes
remove unneeded layout layer in timer_list_item
remove unneeded landscape timer_list_item

Change-Id: Id67e1120c86679c03b55f5b6d714cac233d37842
(cherry picked from commit c9524f8b)