Just in case anyone was wondering why the client needed to be updated, I changed the party protocol a bit, and it's kind of unextensible, so the old client would have crashed anyway if it received the new party messages.
The changes were mostly under-the-hood. The changes you'll see visibly are two:
* When someone is inside a house or similar, his arrow will disappear rather than point to nonsense places.
* The colors of the party members are kept on the server now, which enabled me to color-code party chat messages according to the color the speaking part has in the party.
EDIT: One more, actually:
* Parties with more members than the fixed five will have random colors assigned to the extra members, rather than them all being black.
EDIT 2: I guess I might as well take this opportunity to announce another mini-feature that's actually been in the client a while now: you can adjust the volume of the sound effects by typing ":sfxvol VOLUME", where VOLUME is a number between 0 and 1. For instance, ":sfxvol 0.25" will set the volume to 25% of normal. It is properly saved between sessions.
That's it.