added a skeleton implementation of a stack (currently unused)
added a skeleton implementation of a stack (currently unused)

CelineBoudier/rapid-router,mikebryant/rapid-router,mikebryant/rapid-router,CelineBoudier/rapid-router,CelineBoudier/rapid-router,CelineBoudier/rapid-router,mikebryant/rapid-router,mikebryant/rapid-router