native table support

[cooper]

I half-fixed Markdown table rendering at #111, but text formatting within the table is wrongly using quiki markup now:

we need native support for tables. that would fix this, plus it's a necessary feature. it can be implemented as a block.

concept

table [ Column 1; Column 2 ]{
    [ Row 1 Col 1; Row 1 Col 2 ];
    [ Row 2 Col 1; Row 2 Col 2 ];
}