Replaced "encoding schemes" with "encoding forms"

Adopted the correct term, formally defined in ISO/IEC 10646. Please
notice that the term "encoding form" is also used with this meaning in
[intro.memory]/1.
[deque.overview] add whitespace
[tuple.general] Fix return type of forward_as_tuple

In [tuple.general], change the return type of forward_as_tuple
from tuple<Types...>, 'Types' in italic monoface, to
tuple<Types&&...> in normal monoface, as it appears in
[tuple.creation].
Fix minor typo, etc.
[tuple.general] Fix forward_as_tuple signature.

Make the signature in the synopsis match the definition in
[tuple.creation].
Merge pull request #41 from jwakely/tuple.general

[tuple.general] Fix forward_as_tuple signature. Thanks to Jonathan Wakely!
[associative] Remove redundant template arguments.

This removes redundant template arguments from [map.overview],
[multimap.overview], [set.overview] and [multiset.overview].

This is consistent with other member functions that rely on the injected
class name and I find it much easier to read the class synopses without
the clutter of the explicit template argument lists.
[istream::sentry] Fix typeface.

Use code typeface for is.setstate(failbit).
[istreambuf.iterator] Fix typeface.

Use code typeface for streambuf_type::sgetc().
Merge pull request #31 from iaanus/master

Replaced "encoding schemes" with "encoding forms". Thanks to Alberto Ganesh Barbati!
Merge pull request #32 from jwakely/deque.overview

[deque.overview] add whitespace. Thanks to Jonathan Wakely!
Merge pull request #36 from smithpaul/forward_as_tuple-fix

[tuple.general] Fix return type of forward_as_tuple. Thanks to Paul Smith!
Merge pull request #38 from kariya-mitsuru/minorfix

[Containers] Fix minor typo, etc. Thanks to Miutsuru kariya!
Merge pull request #42 from jwakely/associative

[associative] Remove redundant template arguments. Thanks to Jonathan Wakely!
Merge pull request #43 from jwakely/io-typeface

Typefaces fixes. Thanks to Jonathan Wakely!