SwRangeRedline::Show() will move nodes around in the nodes-array, which
means that using SwNodeIndex as a key in a map that has a lifetime
not limited by the stack is a bad idea, as the map will become unsorted.

Remove SwFrmFmtAnchorMap from SwDoc and replace it with new
SwNode::m_pAnchoredFlys to do the same mapping.

(regression from 738fb2ad)

Change-Id: I396d92b9d0b2045e98bad6d0b374303cd4e62b59