On branch ch15
	renamed:    ch15/matrix_chain.hpp -> ch15/matrix_chain_order.hpp
working on matrix chain multiply
 On branch ch15
	modified:   ch15/matrix_chain_mutiply.hpp
move matrix multiplication and <<= into boost.
	modified:   ch15/matrix.hpp
	modified:   ch15/matrix_chain_mutiply.hpp
add a few functions into boost matrix
	modified:   ch15/matrix.hpp