Table page-break improvements

Bump tables to the next page if we cannot fit the caption, thead
and first cell on the current page. Ideally this should be checking
the height of all cells in the first row in the same manner as is
done in the table section render but as this is more of a nice to
have I've done the minimal amount of work for now.

We now only layout section rows once each section has been positioned
within the table, and only supply head and foot reservation heights
to the appropriate sections.

When re-drawing the thead and tfoot only do so if the rect we are
painting is explicitly before/after the "original" thead/tfoot
rather than simply outside of its boundaries. This prevents issues
with re-drawing a redundant head when bumping tables to the next page.

Re-work the table section row layout code so that it's a bit more
streamlined. Additionally, to cater for cells spanning multiple rows
we avoid page breaks in the middle of their content. Note that rows
are always bumped to the next page even if their content doesn't
fit on a full page so as to avoid daft situtations like having the
first 1px on the preceeding page.