Increase chicken delta period from 6 to 12 hours.

We should not ask students to "don't sleep" for the 6 hours period.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5888 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
chicken.getting_old: ok, let's make it 0.9 for every 24 hrs.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5889 63ad8ddf-47c3-0310-b6dd-a9e9d9715204