make alpha guess a bit smarter by adapting it to the level of beta,
lower upper bound for nu guess, remove transformation of guess which
is wrong here (it rather seems to belong to the code commented out above)
fix computation of row index when populating the result matrix,
add inspector for swap lengths,
make exception messages more expressive
add calibration to a termstructure of betas,
use transformed variables in optimization instead of constraints
update the parameter guess only if a parameter guess quote changes and not on each notification, because
otherwise e.g. a calibrated beta structure is lost on each such update,
add option for backward flat SABR parameters, deduce default acceptance level from max error,
allow for recalibration with beta termstructure
add backward flat / linear interpolation
add new file to makefile
simplify formula
Merge branch 'cmsmarket'

Conflicts:
	QuantLib/ql/math/interpolations/backwardflatlinearinterpolation.hpp
	QuantLib/ql/math/interpolations/sabrinterpolation.hpp
	QuantLib/ql/termstructures/volatility/swaption/cmsmarketcalibration.hpp
	QuantLib/ql/termstructures/volatility/swaption/swaptionvolcube1.cpp
	QuantLib/ql/termstructures/volatility/swaption/swaptionvolcube1.hpp