Merge branch 'develop' into ELASTIX-71-Create-functional-components

CMake/elxModules.cmake

CMakeLists.txt

Modules/Components/Elastix/ModuleElastix.cmake

Modules/Components/Elastix/include/elxElastixFilter.h

Modules/Components/Elastix/include/elxElastixFilter.hxx

Modules/Components/Elastix/include/elxTransformixFilter.h

Modules/Components/Elastix/include/elxTransformixFilter.hxx

Modules/Core/ModuleCore.cmake

Modules/Core/ParameterObject/include/elxParameterObject.h

SuperBuild/CMakeLists.txt

SuperBuild/ExternalElastix.cmake

Testing/Unit/CMakeLists.txt

Testing/Unit/elxElastixFilterTest.cxx

Testing/Unit/elxTransformixFilterTest.cxx