Removing now unsupported configure script
Preparing CMakeLists.txt for unit-tests, added add_unittest.cmake

Next step on transitioning to CMake. In the future we'll use CMake to
build and run unit-tests. For this I wrote the add_unittest.cmake file
which implements the add_unittest() function wrapping a bunch of CMake
functions for easier writing of new unit-tests.
Removing Core::TemplateEngine