Merge pull request #824 from jmdavis/time

Revert "Fix for 12837: Duration's get and individual unit getters are bug-prone.
Fix for 12837: Duration's get and individual unit getters are bug-prone.

Experience has shown that most people (at least some of who don't read
the documentation) seem to expect that get and the indivdual getters
return what total returns, causing bugs. So, this commit renames get to
extract (leaving get as a deprecated alias to extract) and deprecates
the individual unit getters, forcing folks to use total or getOnly
explicitly. It's likely that most code that will have to change because
of these changes is broken anyway, so this will catch bugs.