Merge branch 'cleansingleton' into develop

Core/FormFactors/FormFactorPolyhedron.cpp

Core/TestMachinery/FunctionalTestRegistry.h

Core/Tools/ISingleton.h

Core/Tools/Precomputed.h

GUI/coregui/mainwindow/AppSvc.cpp

GUI/coregui/mainwindow/AppSvc.h

Tests/UnitTests/Core/3/PrecomputedTest.h

auto/Wrap/doxygen_core.i

auto/Wrap/doxygen_fit.i

auto/Wrap/libBornAgainCore.py

auto/Wrap/libBornAgainCore_wrap.cpp

auto/Wrap/libBornAgainCore_wrap.h

auto/Wrap/libBornAgainFit.py

auto/Wrap/libBornAgainFit_wrap.cpp

auto/Wrap/libBornAgainFit_wrap.h