Merge https://github.com/bobbthebuilder/stxxl-doc

Conflicts:
	include/stxxl/bits/containers/deque.h
	include/stxxl/bits/containers/map.h
	include/stxxl/bits/containers/matrix.h
	include/stxxl/bits/containers/priority_queue.h
	include/stxxl/bits/containers/queue.h
	include/stxxl/bits/containers/sorter.h
	include/stxxl/bits/containers/stack.h
	include/stxxl/bits/containers/vector.h