Fixed a crash when generating a chest

git-svn-id: http://mc-server.googlecode.com/svn/trunk@1549 0a769ca7-a7f5-676a-18bf-c427514a06d6
DistortedHeightmap: Added clay / sand / dirt selection on ocean floor

git-svn-id: http://mc-server.googlecode.com/svn/trunk@1550 0a769ca7-a7f5-676a-18bf-c427514a06d6