This fixes a regression introduced by fb77678e.

Since the table row start is inserted after the rest of the table is
inserted, the cursor is saved, and temporarily moved to the start of the
row to insert the table row start paragraph.  Unfortunately the
paragraph in saved cursor becomes invalid during this insertion and
needs to be updated, so this code introduced a regression once
paragraphs started to be stored in cursors.

Style objects are referenced counted in richedit controls, so I tried to
make sure styles were released properly.  This can be checked using with
the all_refs global reference count to see if everything is cleaned up.

Previously inserting the object didn't result in the text being wrapped,
which would cause an assertion error when this is checked for during
repainting the text.  It is also important to invalidate the affected
areas of text, update the scrollbar, and end the creation of undo
transactions for this insertion.

Reported by Paul Vriens.