Weasyprint requires at least lxml 3.0
Merge pull request #153 from graingert/patch-1

Weasyprint requires at least lxml 3.0
[docs] lxml 3.0 is required, see #147
When determining the table_cell width, table.width needs also be checked whether it equals 'auto'.
Fix up and merge pull request #152 from nexxar/master

Fix #152