PhP error handling texts that has special signs (e.g. apostrophes)

[oliverglanz]

Whenever there are words that have an apostrophe contained ("brother's widow") a PHP error appears:

The problem also shows up in vocabulary exercises when unicodes are being used for apostrophes rather than the "normal" writing.

The problem also seems to affect other parts of BibleOL. In the grading of exercises or exams the table showing the list of students is partly disfunctional when the name of a user contains an apostrophe or full stop.