Hervé Girod - 2019-02-14

Add a "tab " element to support tabs
docx: fix styles for table header columns which were not correctly set
docx: fix captions in tables which were incorrectly set
docx: handle column and cell backgrounds in CSS
docx: fix some cases where an image position in the chapter was wrong
docx and pdf: allow to show the glossary
pdf: handle sentences color and background color
pdf: support titles colors
pdf: support sentence colors and background colors
pdf: support table captions font types
pdf: support table header background colors
pdf: support cells text color and size
pdf: handle tables with no borders
pdf: handle table cells styles
pdf: handle references styles