(bug #56686) Use exponent to represent sig digits

Change-Id: Idf91f194dde9748a508ff47495c8b09c110f8a1d
(bug #56714) option for disabling rounding.

The rounding applied to QuantityValues is now configurable
via an option key.

Change-Id: Ieea60f847923a3e5ac26cc5ee08dc0e3dfada8ad
Merge changes Ieea60f84,Idf91f194

* changes:
  (bug #56714) option for disabling rounding.
  (bug #56686) Use exponent to represent sig digits