paraparser.py: improved checking on <a> tag attributes
paraparser.py: improved checking on <a> tag attributes

Distrotech/reportlab,kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,kanarelo/reportlab,kanarelo/reportlab,Distrotech/reportlab,Distrotech/reportlab