As Paul points out, links of the form [@boost:/libs/something/index.html] (as
recommended by
http://www.boost.org/doc/libs/release/doc/html/quickbook/syntax/phrase.html#quickbook.syntax.phrase.links)
do not work when generating PDF, or even when locally generating just one
library's HTML documentation. He suggests linking explicitly to the relevant
boost.org URL. This is much more satisfying as the link can be tested.
Add note explaining why synchronization objects can neither be moved nor
copied.
Introduce line breaks for some code lines that get broken strangely by doc
toolchain.
Eliminate reference to mutex::scoped_lock.