Fix #44: bad interaction of `page-break-before/after: avoid` and floats.
Fix #44: bad interaction of `page-break-before/after: avoid` and floats.

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