Add mgrow.{cc,h} to the Xcode project.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@2631 c06c8d41-db1a-0410-9941-cceddc491573

Created by  nlanza  on October 27, 2007
I46VPTZN4UTGKQWLQSQZCLJVXTYHNHIYH7KKZZXTHYSXUZZVHECAC
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