Log Message:
inspircd3: Update to 3.1.0

Changes:

* Added a configure option, --disable-auto-extras, which disables
automatically enabling extras for which the dependencies are
available.
* Added support for disabling a STS policy for users in specific
connect classes.
* Added support for the IRCv3 Message IDs specification.
* Fixed a crash in the silence module on some older versions of
GCC.
* Fixed linking against v2 servers running the ASCII case mapping
module from inspircd-extras.
* Fixed an inverted condition in the commonchans module which made
the module not work.
* Fixed configure not failing when invalid options were passed to
it.
* Fixed pending X-lines only being applied to a single user.
* Fixed servers not specifying whether they are hidden. If no
visibility is specified then servers default to the visibility of
their parent server.