#1691 Python3: /common Security Fixes: isbn.py, navbar.py, authorClass.py, awardClass.py

[Al von Ruff]

isbn.py

• Fixed bare excepts: clauses (Portability / Readability)
• Changed the variable 'sum' to 'localSum'. 'sum' is a built-in Python keyword

navbar.py

• ISFDBText promoted to module-level import; redundant local import in PrintSearchBox removed
• PrintLoggedIn: username wrapped with ISFDBText()
• PrintMessagesLink: username URL-encoded in hrefs via Portable_urllib_quote()
• PrintWikiPointer: submitter URL-encoded in href, HTML-escaped in display text
• Removed unnecessary return statements

authorClass.py

• xml2obj: NodeList compared against 0. getElementsByTagName() returns a NodeList, never an integer.
• Portability: raise-as-control-flow replaced

awardClass.py

• Portability: raise-as-control-flow replaced
• Security: award_title output raw to HTML
• Removed self import of awardClass