[crossfire] Quests & such

[Nicolas Weeger]

Hello.

I was thinking of implementing a quest system. I see 2 options:
* use forces to keep information. Something like a force with slaying
"quest <name> <tag>". This way detectors & markers can be used simply
as they are. I'd just add 2 special tags, "start" and "end", the first
being active when the quest is running, the second removing all
<name>-related tags to prevent restarting quest.
* or create new fields to store information.

In all cases, talk_to_xxx (or rather find_matching_message) will need
to be changed to allow a "quest <name> <tag>" on first line, to only
say text when player does have the force name.

For me the first method sounds better, as it lets manipulate quest
items simply, and for instance put limits on realizing tasks (with
force decay). Of course, it means more items in player inventory, but
i guess we can live with that :)
I'll just go ahead & implement that.

Nicolas