Fix strings, stability bug, easy UI & correctness issues

Bug: 20625562
Bug: 20649711
Bug: 20561890
Bug: 20561528
Bug: 20442590
Bug: 15473140
Bug: 20503008
Bug: 20503007

- Improve timeout text.

- Recalculate when Calculator is rotated, e.g. in error state, thus
  reproducing message.  It's unclear this is good enough, but it's
  better.

- Fix square root parsing.

- Fix concatenation of numbers when pasting by adding explicit
  multiplication.

- Display divide by zero error differently from other domain errors.

- Improved advanced keypad layout of portrait-mode tablet calculator.

- Improved overflow menu order.  (More to be done.)

- Report zero division as zero division when we can recognize it.

- Switch to floating menus for copy/paste.

Change-Id: I3875414f293e62a59b0e41f0de822f29bd5ac6a6