Re #4158. Made Fit work via AlgorithmProxy

Code/Mantid/Framework/API/CMakeLists.txt

Code/Mantid/Framework/API/inc/MantidAPI/AlgorithmProxy.h

Code/Mantid/Framework/API/inc/MantidAPI/FunctionValues.h

Code/Mantid/Framework/API/inc/MantidAPI/IFunction.h

Code/Mantid/Framework/API/inc/MantidAPI/IFunctionValues.h

.../Mantid/Framework/API/inc/MantidAPI/MultiDomainFunction.h

Code/Mantid/Framework/API/src/AlgorithmProxy.cpp

Code/Mantid/Framework/API/src/FunctionValues.cpp

Code/Mantid/Framework/CurveFitting/CMakeLists.txt

...ork/CurveFitting/inc/MantidCurveFitting/CompositeValues.h

...ork/CurveFitting/inc/MantidCurveFitting/CostFuncFitting.h

...antid/Framework/CurveFitting/inc/MantidCurveFitting/Fit.h

...tid/Framework/CurveFitting/inc/MantidCurveFitting/FitMD.h

...tid/Framework/CurveFitting/inc/MantidCurveFitting/FitMW.h

...work/CurveFitting/inc/MantidCurveFitting/IDomainCreator.h

.../CurveFitting/inc/MantidCurveFitting/MultiDomainCreator.h

Code/Mantid/Framework/CurveFitting/src/CostFuncFitting.cpp

...antid/Framework/CurveFitting/src/CostFuncLeastSquares.cpp

Code/Mantid/Framework/CurveFitting/src/Fit.cpp

Code/Mantid/Framework/CurveFitting/src/FitMD.cpp