abstract out the projection from ProjectedCostFunction and add a ProjectedConstraint class
allow for calibration of a subset of the model's parameters
add a calibration constraint which fixes the mean reversion during calibration
add a calibration constraint which fixes the first component of the piecewise volatility,
overwrite the calibrate method to make this constraint the default
add a test case for calibration with fixed reversion parameter
amend the test case for the calibration to a secondary instrument set
Merge branch 'fix20131025'

Conflicts:
	QuantLib/ql/experimental/models/markovfunctional.hpp
	QuantLib/ql/models/model.cpp

Adapt gsr model and associated examples to new design of CalibratedModel