Use a better algorithm for border-style: ridge/groove/inset/outset (fix #78)
Use a better algorithm for border-style: ridge/groove/inset/outset (fix #78)

andrewleech/WeasyPrint,prepare/TestWeasyPrint,Kozea/WeasyPrint,jasco/WeasyPrint,jasco/WeasyPrint,andrewleech/WeasyPrint,marclaporte/WeasyPrint,marclaporte/WeasyPrint,prepare/TestWeasyPrint,Kozea/WeasyPrint