csprd03 - PR on removing annotations

In section "4.7.3 Annotations" there is the following PR:

[[
When a Modifier removes an <mrk> element or a pair of <sm> / <em> elements and the ref attribute is present, it MUST check whether
or not the URI referenced by the ref attribute is within the same <unit> as the removed element. If it is and no other element has a
reference to the referenced element, the Modifier MUST remove the referenced element.
]]

There was several issues related to it that were brought up (see https://lists.oasis-open.org/archives/xliff/201311/msg00054.html)
most issues were resolved with the definition of the Fragment Identifier mechanism.

However, the last issue listed was forgotten and is still present: This PR is too difficult to implement and needs to be removed.
It looks like (informally) there was not dissent on that (See https://lists.oasis-open.org/archives/xliff/201311/msg00117.html) but
it was never formally done.


-yves