Add option to disable building the bindings.

If you want to disable them, even if SWIG and Python were both found, set
WITH_BINDINGS to NO with -DWITH_BINDINGS=NO or in the CMake GUI.

CMakeLists.txt

@@ -74,6 +74,7 @@ MESSAGE(STATUS "Static libraries:    " ${BUILD_STATIC_LIBRARIES})
 MESSAGE(STATUS "Dynamic libraries:   " ${BUILD_DYNAMIC_LIBRARIES})
 MESSAGE(STATUS "Build examples:      " ${ENABLE_EXAMPLES})
 MESSAGE(STATUS "Build tests:         " ${BUILD_TESTING})
+MESSAGE(STATUS "Build bindings:      " ${BUILD_BINDINGS})
 MESSAGE(STATUS "API Docs available:  " ${DOXYGEN_FOUND})
 MESSAGE(STATUS " - Qt Help bundling: " ${BUILD_AND_BUNDLE_DOCS})
 MESSAGE(STATUS "Build manual:        " ${BUILD_MANUAL})