Some more documentation for tabular.lua
Template for mathjax in sourcedoc
Schema / documentation for collapse
Border-collapse for horizontal cells

This is the easy case: no problems with splitting tables
Vertical border-collapse

Note: cases where rowspan > 1 will be handled later on.
* bordercollapse:
  Vertical border-collapse
  Border-collapse for horizontal cells
  Schema / documentation for collapse
Default h-alignment of td now "left"

Due to a global variable, the default alignment of the table cell was
somewhat non-deterministic.