Tweak Yred's soul-marking duration one more time.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@10384 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on July 23, 2009
SYR5Y64465KVHPZDK7BYEYYZ3HSANOJV37I7MJ3VGQXQB4L4CZSQC
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