m_ssl_gnutls Create GNUTLS_NEW_CERT_CALLBACK_API and cert_cb_last_param_type
Add the ability to have multiple SSL profiles

SSL profiles are now used instead of fixed SSL settings for everything
SSL, making it possible to use completely different settings for each
listener and outgoing connection.

Outgoing connections are broken until the next commit.
Split IOHook into IOHook and IOHookProvider

Create one IOHook instance for each hooked socket which contains all the
hook specific data and read/write/close functions, removing the need for
the "issl_session" array in SSL modules.

Register instances of the IOHookProvider class in the core and use them to
create specialized IOHook instances (OnConnect/OnAccept).

Remove the OnHookIO hook, add a dynamic reference to ListenSocket that
points to the hook provider (if any) to use for incoming connections on
that socket.

For outgoing connections modules still have to find the IOHookProvider
they want to use themselves but instead of calling AddIOHook(hookprov),
now they have to call IOHookProvider::OnConnect() after the connection
has been established.
Remove unneeded classbase inheritance from FileReader
Globally #undef min and max on Windows
Remove whitespace and minor style changes
Add intrusive list template
Convert UserChanList to an intrusively linked list
Convert LocalUserList to an intrusively linked list
cmd_invite Fix incorrect parameter being passed to InspIRCd::Duration()
Remove classbase inheritance from Invitation
Convert InviteBase::invites to an intrusively linked list
Destroy Memberships of a quitting user in QuitUser() instead of in cull()
Convert InspIRCd::PassCompare to return bool instead of int.

The insane behaviour of this method was due to an implementation
detail which has since become irrelevent.