[FIX] selections: Rollback r47762 (fix for IE10+ selection replacement in insertAt...) and fix "upstream" in fn.selection so correct text appears in dialog tools.
In IE10 the range's htmlText now uses unix line ends, which is what's used elsewhere, as opposed to two char (windows) line ends used in IE8 which need to be considered in the start/end position calculation in insertAt.
Tested in IE10 and IE8.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@47953 b456876b-0849-0410-b77d-98878d47e9d5