Merged revisions 79756 via svnmerge from

Merged revisions 79756 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r79756 | mark.dickinson | 2010-04-04 23:09:21 +0100 (Sun, 04 Apr 2010) | 6 lines

  Add versionchanged entry for Decimal(float) construction.

  Also add an example of constructing a Decimal directly from a float,
  update the quickstart tutorial, and tweak another couple of
  sentences.
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