Improved calibration by allowing different starting points.

A result is returned as soon as the calibration error is below
the given value; otherwise, the parameters yielding the least
error are returned.

Thanks to Peter Caspers.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18472 8618b1d8-e22c-0410-b026-96a5dba3e089
Inherited CalibrationHelper from LazyObject (thanks to Peter Caspers).

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18473 8618b1d8-e22c-0410-b026-96a5dba3e089
Replaced update() call during calibration with explicit method calls.

The generateArguments() and notifyObservers() methods are called directly.
This allows to separate the smile update triggered by market data change
from the numeraire update triggered by model volatility changes.

Thanks to Peter Caspers.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18474 8618b1d8-e22c-0410-b026-96a5dba3e089
Added smileSectionImpl() implementation using cubic interpolation.

Thanks to Peter Caspers.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18475 8618b1d8-e22c-0410-b026-96a5dba3e089
Floored the strike at 0.1bp for volatility computation.

This avoids problems for strikes near zero.

Thanks to Peter Caspers.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18476 8618b1d8-e22c-0410-b026-96a5dba3e089
Filtered out negative strikes (thanks to Peter Caspers).

Also, calibration results were improved by using the functionality
recently added to SABR interpolation.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18477 8618b1d8-e22c-0410-b026-96a5dba3e089
Added experimental Markov functional model (thanks to Peter Caspers).

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18478 8618b1d8-e22c-0410-b026-96a5dba3e089
Fixed a few Mexican holidays.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18479 8618b1d8-e22c-0410-b026-96a5dba3e089
Added moving holidays for 2013.

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18480 8618b1d8-e22c-0410-b026-96a5dba3e089