Merge branch 'modernize-gaudigsl' into 'master'

GaudiGSL/CMakeLists.txt

GaudiGSL/GaudiGSL/GaudiGSL.h

GaudiGSL/GaudiGSL/GslError.h

GaudiGSL/GaudiGSL/IEqSolver.h

GaudiGSL/GaudiGSL/IFuncMinimum.h

GaudiGSL/GaudiGSL/IGslErrorHandler.h

GaudiGSL/GaudiGSL/IGslSvc.h

GaudiGSL/GaudiMath/Constant.h

GaudiGSL/GaudiMath/FunAdapters.h

GaudiGSL/GaudiMath/GSLFunAdapters.h

GaudiGSL/GaudiMath/Interpolation.h

GaudiGSL/GaudiMath/NumericalDefiniteIntegral.h

GaudiGSL/GaudiMath/NumericalIndefiniteIntegral.h

GaudiGSL/GaudiMath/Splines.h

GaudiGSL/dict/GaudiGSLMath.xml

GaudiGSL/src/Components/EqSolver.cpp

GaudiGSL/src/Components/EqSolver.h

GaudiGSL/src/Components/FuncMinimum.cpp

GaudiGSL/src/Components/FuncMinimum.h

GaudiGSL/src/Components/GslErrorCount.cpp