Removed explicit conversions from pointer to shared_ptr.

They're no longer valid on all compilers.
Generated ChangeLogs for version 1.3.

They are now simply the output of
$ git log --pretty=medium --date=rfc
for the required changesets.
Updated list of contributors.
Updated news for QuantLib 1.3.
Fixed reference dates for yield-based npv calculation.

Thanks to Nick Glass for the heads-up.
Using correct #define to check for x64 compilation.

This also removes the need to add a custom preprocessor definition
to the projects.
Also, the check was extended to VC++10 and 11.

Thanks to Dale Smith for the heads-up and the analysis.
Added warnings for reported test failures on Mac OS X 10.8.4.

Thanks to Richard Stanton for the report.
correct non matching #ifndef #define