Actual encryped messages and notices are now printed directly from do_sed() / do_reply_sed().
Inline CTCP replacement is only done if the message cannot be decrypted (for the [ENCRYPTED MESSAGE]
placeholder).
This removes the need for the global flag 'sed' to alter the NOTICE and PRIVMSG handling.
A side-effect of this is that SED PRIVMSGs now do not go through the usual PRIVMSG ignore
and flood handling. This is acceptable because messages can only go through this path if
the sender has actually been added as a SED peer with /ENCRYPT, and it still goes through
the CTCP ignore and flood handling.
Tokens that begin with two underscores __* or an underscore and an uppercase letter _X* are reserved,
so we should avoid those for our own include guards. The standard I'm settling on for foo.h is FOO_H_.
