This means the calling code in commands.c no longer needs to take a copy before calling the function.
Also remove code testing result of of ctcp_quote_it() and ctcp_unquote_it() - these functions never fail.
These functions are really specific to parsing and creating CTCP SED messages, which means they belong
in ctcp.c with the other CTCP code.
Also remove unnecessary inclusions of encrypt.h and ctcp.h.
Use size_t for passing buffer lengths, and const char * for encryption keys and other non-modified buffer
arguments.
Remove pointless helper function do_crypt().
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_.
