add nodeSucc for ex12.3-5
 On branch ch12
	modified:   ch12/node.hpp
first commit on binary_search_tree_succ
 On branch ch12
	new file:   ch12/binary_search_tree_succ.hpp
add insert() ,tested.
 On branch ch12
	modified:   ch12/binary_search_tree_succ.hpp
	modified:   ch12/node.hpp
add search()
 On branch ch12
	modified:   ch12/binary_search_tree_succ.hpp
add maximum and minimum
 On branch ch12
	modified:   ch12/binary_search_tree_succ.hpp
add predecessor
 On branch ch12
	modified:   ch12/binary_search_tree_succ.hpp