Reverted: 2e099caceb9..21102938e8ccb
I'm going to reapply some of them soon, but it's easier to revert them
all first, as there are conflicts. Also the number of changes that were
inserted since then, mean that there would be a huge gap between related
changes.
for handling vc6/7 deficiencies with iterator_traits.
Fixed a bug in iterator_facade which was causing incomplete types to
be passed through is_convertible.
Reinstated libs/utility/iterator_traits_test.cpp
[SVN r19840]
