sw: rename SwFrm::Remove to something unique

Change-Id: I4daf01450a4aa8f1d2bc6eae731a735d0d38a074
fdo#87199: sw: fix root cause of a11y crash when merging cells

Commit f9eff2a402a4cd28d7dbfb6ce27cbf96b31e576f is not quite right
because it will leave the mpNext chain unreachable; that could perhaps
be imporoved by calling RemoveFromLayout(), but...

Actually the problem is basically that one of the deleted SwCellFrms
points to a SwTableBox with getRowSpan() -1 (because it has been merged)
and thus IsInCoveredCell() returns true and that causes ~SwCellFrm() to
skip disposing the SwAccessible stuff, so the SwCellFrm is still
contained in the SwAccessibleMap.

Because it's rather hard to prevent this sort of thing in general,
better change SwAccessibleMap::Dispose() to assume that if it found its
way into the SwAccessibleMap it should be disposed and removed.

Change-Id: Ib4cec6924cb026ae30bdac6857957adf237b4d70
sw: prefix SwLayoutFrm members

Change-Id: If961ecfe27c6f478f030bab746278b885482b229
sw: prefix SwCellFrm members

Change-Id: Ia38bdf402595dc0b7e6dabd80a4e93e53142b719
sw: prefix SwRowFrm members

Change-Id: I262efe47d8a28d1462cf35314a99c4404ffa2200
sw: prefix SwTabFrm members

Change-Id: If2de38d23c5753e703517b5ef82d0f00070c2f34