[BC change] remove duplicated data properties

[comment:nid] duplicates [comment:node:nid]
[comment:uid] duplicates [comment:author:uid]
[comment:subject] duplicates [comment:title]
[node:uid] duplicates [node:author:uid]
[file:uid] duplicates [file:owner:uid]
..

In short, the idea is to remove duplicated properties like [node:uid] in favour of the chained properties [node:author:uid]. This would mean any Rules already making use of node:uid would need an update to use the chained variant. Options on that? -> Please respond to the original issue:

http://drupal.org/node/975616#comment-3730162