Iterator: Remove use of eti baseclass workaround.

[SVN r85940]
Iterator: Remove obsolete GCC version check.

[SVN r86055]
Remove use of BOOST_ITERATOR_CATEGORY

[SVN r86056]
Iterator: Remove obsolete MSVC version checks.

[SVN r86082]

Conflicts:
	include/boost/iterator/iterator_facade.hpp
BOOST_ITERATOR_CATEGORY shouldn't be removed.

Since it was documented, it should be kept for backwards compatiblity.
Rebuild iterator_traits.html using latest docutils.
Remove the the broken compiler notes.

Now that the workarounds have been removed, they no longer apply.
Merge branch 'feature/remove-old-compiler-support' into develop