Allow BM deleting illegal contents.

Since this may be sensitive, we need sysop/groupop to explicitly set it.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5915 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
Revise mask_content messages.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5916 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
Revise mask_content message, again.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5917 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
Prevent people entering board symlinks and incorrectly set its targets (without
permission).


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5918 63ad8ddf-47c3-0310-b6dd-a9e9d9715204