improved checkout.html and initial returns commit

todo: notify holdee(returns), testing
implemented return functionality
update return functionality

retrieves email in qresult and book info in qbook
implementation of checkout and return

checkout only one item at a time
return error coverage

returning a book that was never taken out
fixed book checkout db inconsistensy
implement overdue report
added success messages
overdue report shows more info
adding without subjects or otherAuthors
merged
halfway
add new book/copy is done
removed old overdue file
report for checked out items done
report for popular books done
bug fix in overdue
fixed bug in layout
removed debugigng messages
overdue implementation bugs