Adds off-the-record (OTR) support to HexChat.

Originally forked from irssi-otr and still a work in progress.

• glib
• gcrypt
• libotr4
• hexchat
• meson

meson builddir -Dlocal_install=true
ninja -C builddir install

meson builddir
ninja -C builddir
sudo ninja -C builddir install

1. Start a session with a user:

   /query nick
   /otr start
   

   If this is your first time it may take a while to generate a key.

2. Authenticate this user:

   At this point you need to verify this is the person you think it is.

   • If you know their fingerprint and it is correct:

      /otr trust
     

   • If you have previously agreed on a shared secret:

      /otr auth <shared secret>
     

   • If you have neither of these:

      /otr authq <question> <answer>
     

3. Start chatting:

   Everything should be secure at this point. When you are done:

   /otr finish