Update configuration for building drafts after N4140.
Add papers N4138, N4139, N4140: New working draft and editor's reports.
Replace 'prototype' with 'declaration'
Merge pull request #388 from tkoeppe/prototype_lite

Replace 'prototype' with 'declaration'
[dcl.fct] Add paragraph breaks into overlong paragraph that covers several
independent topics.
[temp.arg.template] Remove some "call it"s.
[temp.deduct.call] Give a name to the function parameter in an example.
Fix formatting of INVOKE
Merge pull request #394 from tkoeppe/INVOKE

Fix formatting of INVOKE
CWG1998 Additional sources of xvalue expressions

Fixed editorially per discussion with CWG; the original wording and
revised wording are normatively equivalent.
N4262 Wording for Forwarding References
[cpp.predefined] Stop trying to reuse a footnote for two different bullets;
that breaks hyperlinking.
N2467 Adding u8 character literals.
N4268 Allow constant evaluation for all non-type template arguments.
N4230 Nested namespace definition
Merge branch 'master' of https://github.com/cplusplus/draft
[bad.exception] Fix indentation of itemdecl contents.
[vector.bool] Use code font for allocator_traits
CWG393 Pointer to array of unknown bound in template argument list in parameter
CWG591 When a dependent base class is the current instantiation

Move the added example inside the note, since it's an example of the note, not
of the language rule.