Pass also const CellRef& to save a lot of getCellByPosition() calls.

Change-Id: I86c89a05d263cada38ff54eaccf9ba39458db52e
(cherry picked from commit 7b9b57b41936eea673eb678407ed817856ba0912)
fdo#76324: Use one static SvXMLTokenMap object, it's faster.

For me it saves ~10% of load time for calc document with 2000 comments.
Thanks to Michael for noticing this oddity.

Change-Id: Id44f44c02df2ae9360d02c28081601f5f7a8ea27
(cherry picked from commit d2e0465d406b33139f3a97e1738020d6a7a6f6c3)