shr.el (shr-tag-table-1): Use bg/gfcolor specs on tables.

shr.el (shr-tag-table-1): Use bg/gfcolor specs on tables.
 (shr-render-td): Handle td style="" better.
 (shr-tag-table): Use the color from the style sheet.
 (shr-render-td): Make sure we copy over all the overlays, too.
nnimap.el (nnimap-parse-flags): Tweak VANISHED regexp to avoid regexp overflow, possibly.